diff --git a/params/config.go b/params/config.go
index 470feb3fc8..c8f755ae6f 100644
--- a/params/config.go
+++ b/params/config.go
@@ -24,6 +24,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/log"
 )
 
 // Genesis hashes to enforce below configs on.
@@ -430,6 +431,7 @@ type Transition struct {
 	EpochLength           uint64   `json:"epochlength,omitempty"`           // Number of blocks that should pass before pending validator votes are reset
 	BlockPeriodSeconds    uint64   `json:"blockperiodseconds,omitempty"`    // Minimum time between two consecutive IBFT or QBFT blocks’ timestamps in seconds
 	RequestTimeoutSeconds uint64   `json:"requesttimeoutseconds,omitempty"` // Minimum request timeout for each IBFT or QBFT round in milliseconds
+	ContractSizeLimit     uint64   `json:"contractsizelimit,omitempty"`     // Maximum smart contract code size
 }
 
 // String implements the fmt.Stringer interface.
@@ -565,6 +567,7 @@ func (c *ChainConfig) GetMaxCodeSize(num *big.Int) int {
 	maxCodeSize := MaxCodeSize
 
 	if len(c.MaxCodeSizeConfig) > 0 {
+		log.Warn("WARNING: The attribute config.maxCodeSizeConfig is deprecated and will be removed in the future, please use config.transitions.contractsizelimit on genesis file")
 		for _, data := range c.MaxCodeSizeConfig {
 			if data.Block.Cmp(num) > 0 {
 				break
@@ -580,6 +583,13 @@ func (c *ChainConfig) GetMaxCodeSize(num *big.Int) int {
 			maxCodeSize = int(c.MaxCodeSize) * 1024
 		}
 	}
+	if len(c.Transitions) > 0 {
+		for i := 0; i < len(c.Transitions) && c.Transitions[i].Block.Cmp(num) <= 0; i++ {
+			if c.Transitions[i].ContractSizeLimit != 0 {
+				maxCodeSize = int(c.Transitions[i].ContractSizeLimit) * 1024
+			}
+		}
+	}
 	return maxCodeSize
 }
 
@@ -623,6 +633,9 @@ func (c *ChainConfig) CheckTransitionsData() error {
 		if c.Istanbul != nil && c.Istanbul.TestQBFTBlock != nil && (transition.Algorithm == IBFT || transition.Algorithm == QBFT) {
 			return ErrTestQBFTBlockAndTransitions
 		}
+		if len(c.MaxCodeSizeConfig) > 0 && transition.ContractSizeLimit != 0 {
+			return ErrMaxCodeSizeConfigAndTransitions
+		}
 		if transition.Algorithm == QBFT {
 			isQBFT = true
 		}
@@ -635,6 +648,9 @@ func (c *ChainConfig) CheckTransitionsData() error {
 		if transition.Algorithm == IBFT && isQBFT {
 			return ErrTransition
 		}
+		if transition.ContractSizeLimit != 0 && (transition.ContractSizeLimit < 24 || transition.ContractSizeLimit > 128) {
+			return ErrContractSizeLimit
+		}
 		prevBlock = transition.Block
 	}
 	return nil
@@ -754,6 +770,9 @@ func isTransitionsConfigCompatible(c1, c2 *ChainConfig, head *big.Int) (error, *
 		if isSameBlock || c1.Transitions[i].EpochLength != c2.Transitions[i].EpochLength {
 			return ErrTransitionIncompatible("EpochLength"), head, head
 		}
+		if isSameBlock || c1.Transitions[i].ContractSizeLimit != c2.Transitions[i].ContractSizeLimit {
+			return ErrTransitionIncompatible("ContractSizeLimit"), head, head
+		}
 	}
 
 	return nil, big.NewInt(0), big.NewInt(0)
diff --git a/params/config_test.go b/params/config_test.go
index ac161509bd..4e15dd544d 100644
--- a/params/config_test.go
+++ b/params/config_test.go
@@ -328,10 +328,10 @@ func TestCheckTransitionsData(t *testing.T) {
 		wantErr error
 	}
 	var ibftTransitionsConfig, qbftTransitionsConfig, invalidTransition, invalidBlockOrder []Transition
-	tranI0 := Transition{big.NewInt(0), IBFT, 30000, 5, 10}
-	tranQ5 := Transition{big.NewInt(5), QBFT, 30000, 5, 10}
-	tranI10 := Transition{big.NewInt(10), IBFT, 30000, 5, 10}
-	tranQ8 := Transition{big.NewInt(8), QBFT, 30000, 5, 10}
+	tranI0 := Transition{big.NewInt(0), IBFT, 30000, 5, 10, 50}
+	tranQ5 := Transition{big.NewInt(5), QBFT, 30000, 5, 10, 50}
+	tranI10 := Transition{big.NewInt(10), IBFT, 30000, 5, 10, 50}
+	tranQ8 := Transition{big.NewInt(8), QBFT, 30000, 5, 10, 50}
 
 	ibftTransitionsConfig = append(ibftTransitionsConfig, tranI0, tranI10)
 	qbftTransitionsConfig = append(qbftTransitionsConfig, tranQ5, tranQ8)
@@ -391,7 +391,7 @@ func TestCheckTransitionsData(t *testing.T) {
 			wantErr: ErrBlockOrder,
 		},
 		{
-			stored:  &ChainConfig{Transitions: []Transition{{nil, IBFT, 30000, 5, 10}}},
+			stored:  &ChainConfig{Transitions: []Transition{{nil, IBFT, 30000, 5, 10, 50}}},
 			wantErr: ErrBlockNumberMissing,
 		},
 		{
@@ -402,6 +402,26 @@ func TestCheckTransitionsData(t *testing.T) {
 			stored:  &ChainConfig{Transitions: []Transition{{Block: big.NewInt(0), Algorithm: ""}}},
 			wantErr: nil,
 		},
+		{
+			stored:  &ChainConfig{MaxCodeSizeConfig: []MaxCodeConfigStruct{{big.NewInt(10), 24}}, Transitions: []Transition{{Block: big.NewInt(0), ContractSizeLimit: 50}}},
+			wantErr: ErrMaxCodeSizeConfigAndTransitions,
+		},
+		{
+			stored:  &ChainConfig{Transitions: []Transition{{Block: big.NewInt(0), ContractSizeLimit: 23}}},
+			wantErr: ErrContractSizeLimit,
+		},
+		{
+			stored:  &ChainConfig{Transitions: []Transition{{Block: big.NewInt(0), ContractSizeLimit: 129}}},
+			wantErr: ErrContractSizeLimit,
+		},
+		{
+			stored:  &ChainConfig{Transitions: []Transition{{Block: big.NewInt(0), ContractSizeLimit: 50}}},
+			wantErr: nil,
+		},
+		{
+			stored:  &ChainConfig{Transitions: []Transition{{Block: big.NewInt(0)}}},
+			wantErr: nil,
+		},
 	}
 
 	for _, test := range tests {
@@ -411,3 +431,58 @@ func TestCheckTransitionsData(t *testing.T) {
 		}
 	}
 }
+
+func TestGetMaxCodeSize(t *testing.T) {
+	type test struct {
+		config      *ChainConfig
+		blockNumber int64
+		maxCode     int
+	}
+	config1, config2, config3 := *TestChainConfig, *TestChainConfig, *TestChainConfig
+	config1.MaxCodeSizeConfig = []MaxCodeConfigStruct{
+		{big.NewInt(2), 28},
+		{big.NewInt(4), 32},
+	}
+	config1.MaxCodeSize = 34
+	config2.MaxCodeSize = 36
+	config2.MaxCodeSizeChangeBlock = big.NewInt(2)
+	config3.MaxCodeSize = 0
+	config3.Transitions = []Transition{
+		{Block: big.NewInt(2), ContractSizeLimit: 50},
+		{Block: big.NewInt(4), ContractSizeLimit: 54},
+	}
+	maxCodeDefault := 32 * 1024
+	tests := []test{
+		{MainnetChainConfig, 0, MaxCodeSize},
+		{RopstenChainConfig, 0, MaxCodeSize},
+		{RinkebyChainConfig, 0, MaxCodeSize},
+		{GoerliChainConfig, 0, MaxCodeSize},
+		{YoloV3ChainConfig, 0, MaxCodeSize},
+		{AllEthashProtocolChanges, 0, 35 * 1024},
+		{AllCliqueProtocolChanges, 0, maxCodeDefault},
+		{TestChainConfig, 0, maxCodeDefault},
+		{QuorumTestChainConfig, 0, maxCodeDefault},
+		{QuorumMPSTestChainConfig, 0, maxCodeDefault},
+		{&config1, 0, MaxCodeSize},
+		{&config1, 1, MaxCodeSize},
+		{&config1, 2, 28 * 1024},
+		{&config1, 3, 28 * 1024},
+		{&config1, 4, 32 * 1024},
+		{&config2, 0, MaxCodeSize},
+		{&config2, 1, MaxCodeSize},
+		{&config2, 2, 36 * 1024},
+		{&config2, 3, 36 * 1024},
+		{&config3, 0, MaxCodeSize},
+		{&config3, 1, MaxCodeSize},
+		{&config3, 2, 50 * 1024},
+		{&config3, 3, 50 * 1024},
+		{&config3, 4, 54 * 1024},
+		{&config3, 8, 54 * 1024},
+	}
+	for _, test := range tests {
+		maxCodeSize := test.config.GetMaxCodeSize(big.NewInt(test.blockNumber))
+		if !reflect.DeepEqual(maxCodeSize, test.maxCode) {
+			t.Errorf("error mismatch:\nexpected: %v\nreceived: %v\n", test.maxCode, maxCodeSize)
+		}
+	}
+}
diff --git a/params/errors.go b/params/errors.go
index 1240177da8..a6aa14a7bf 100644
--- a/params/errors.go
+++ b/params/errors.go
@@ -6,11 +6,13 @@ import (
 )
 
 var (
-	ErrTransitionAlgorithm         = errors.New("transition algorithm is invalid, should be either `ibft` or `qbft`")
-	ErrBlockNumberMissing          = errors.New("block number not given in transitions data")
-	ErrBlockOrder                  = errors.New("block order should be ascending")
-	ErrTransition                  = errors.New("can't transition from qbft to ibft")
-	ErrTestQBFTBlockAndTransitions = errors.New("can't use transition algorithm and testQBFTBlock at the same time")
+	ErrTransitionAlgorithm             = errors.New("transition algorithm is invalid, should be either `ibft` or `qbft`")
+	ErrBlockNumberMissing              = errors.New("block number not given in transitions data")
+	ErrBlockOrder                      = errors.New("block order should be ascending")
+	ErrTransition                      = errors.New("can't transition from qbft to ibft")
+	ErrTestQBFTBlockAndTransitions     = errors.New("can't use transition algorithm and testQBFTBlock at the same time")
+	ErrMaxCodeSizeConfigAndTransitions = errors.New("can't use transition ContractSizeLimit and MaxCodeSizeConfig at the same time")
+	ErrContractSizeLimit               = errors.New("transition contract code size must be between 24 and 128")
 )
 
 func ErrTransitionIncompatible(field string) error {