diff --git a/consensus/parlia/parlia.go b/consensus/parlia/parlia.go
index 323daf2973..4338f83e15 100644
--- a/consensus/parlia/parlia.go
+++ b/consensus/parlia/parlia.go
@@ -336,7 +336,10 @@ func (p *Parlia) verifyHeader(chain consensus.ChainReader, header *types.Header,
 	if len(header.Extra) < extraVanity+extraSeal {
 		return errMissingSignature
 	}
-
+	// Verify that the gasUsed is <= gasLimit
+	if header.GasUsed > header.GasLimit {
+		return fmt.Errorf("invalid gasUsed: have %d, gasLimit %d", header.GasUsed, header.GasLimit)
+	}
 	// check extra data
 	isEpoch := number%p.config.Epoch == 0
 
@@ -742,6 +745,10 @@ func (p *Parlia) FinalizeAndAssemble(chain consensus.ChainReader, header *types.
 	if err != nil {
 		panic(err)
 	}
+	// should not happen. Once happen, stop the node is better than broadcast the block
+	if header.GasLimit < header.GasUsed {
+		panic("Gas consumption of system txs exceed the gas limit")
+	}
 	header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
 	header.UncleHash = types.CalcUncleHash(nil)
 
diff --git a/miner/worker.go b/miner/worker.go
index 79272fe870..f0c622d181 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -732,6 +732,7 @@ func (w *worker) commitTransactions(txs *types.TransactionsByPriceAndNonce, coin
 
 	if w.current.gasPool == nil {
 		w.current.gasPool = new(core.GasPool).AddGas(w.current.header.GasLimit)
+		w.current.gasPool.SubGas(params.SystemTxsGas)
 	}
 
 	var coalescedLogs []*types.Log
diff --git a/params/protocol_params.go b/params/protocol_params.go
index ab5411d2e0..d759305cac 100644
--- a/params/protocol_params.go
+++ b/params/protocol_params.go
@@ -19,21 +19,22 @@ package params
 import "math/big"
 
 const (
-	GasLimitBoundDivisor uint64 = 256    // The bound divisor of the gas limit, used in update calculations.
+	GasLimitBoundDivisor uint64 = 256     // The bound divisor of the gas limit, used in update calculations.
 	MinGasLimit          uint64 = 5000    // Minimum the gas limit may ever be.
 	GenesisGasLimit      uint64 = 4712388 // Gas limit of the Genesis block.
 
-	MaximumExtraDataSize  uint64 = 32    // Maximum size extra data may be after Genesis.
-	ExpByteGas            uint64 = 10    // Times ceil(log256(exponent)) for the EXP instruction.
-	SloadGas              uint64 = 50    // Multiplied by the number of 32-byte words that are copied (round up) for any *COPY operation and added.
-	CallValueTransferGas  uint64 = 9000  // Paid for CALL when the value transfer is non-zero.
-	CallNewAccountGas     uint64 = 25000 // Paid for CALL when the destination address didn't exist prior.
-	TxGas                 uint64 = 21000 // Per transaction not creating a contract. NOTE: Not payable on data of calls between transactions.
-	TxGasContractCreation uint64 = 53000 // Per transaction that creates a contract. NOTE: Not payable on data of calls between transactions.
-	TxDataZeroGas         uint64 = 4     // Per byte of data attached to a transaction that equals zero. NOTE: Not payable on data of calls between transactions.
-	QuadCoeffDiv          uint64 = 512   // Divisor for the quadratic particle of the memory cost equation.
-	LogDataGas            uint64 = 8     // Per byte in a LOG* operation's data.
-	CallStipend           uint64 = 2300  // Free gas given at beginning of call.
+	MaximumExtraDataSize  uint64 = 32     // Maximum size extra data may be after Genesis.
+	ExpByteGas            uint64 = 10     // Times ceil(log256(exponent)) for the EXP instruction.
+	SloadGas              uint64 = 50     // Multiplied by the number of 32-byte words that are copied (round up) for any *COPY operation and added.
+	CallValueTransferGas  uint64 = 9000   // Paid for CALL when the value transfer is non-zero.
+	CallNewAccountGas     uint64 = 25000  // Paid for CALL when the destination address didn't exist prior.
+	TxGas                 uint64 = 21000  // Per transaction not creating a contract. NOTE: Not payable on data of calls between transactions.
+	SystemTxsGas          uint64 = 100000 // The gas reserved for system txs; only for parlia consensus
+	TxGasContractCreation uint64 = 53000  // Per transaction that creates a contract. NOTE: Not payable on data of calls between transactions.
+	TxDataZeroGas         uint64 = 4      // Per byte of data attached to a transaction that equals zero. NOTE: Not payable on data of calls between transactions.
+	QuadCoeffDiv          uint64 = 512    // Divisor for the quadratic particle of the memory cost equation.
+	LogDataGas            uint64 = 8      // Per byte in a LOG* operation's data.
+	CallStipend           uint64 = 2300   // Free gas given at beginning of call.
 
 	Sha3Gas     uint64 = 30 // Once per SHA3 operation.
 	Sha3WordGas uint64 = 6  // Once per word of the SHA3 operation's data.