diff --git a/accounts/abi/bind/backends/simulated.go b/accounts/abi/bind/backends/simulated.go
index b7c93cf479a9..7b786d832c38 100644
--- a/accounts/abi/bind/backends/simulated.go
+++ b/accounts/abi/bind/backends/simulated.go
@@ -160,12 +160,6 @@ func NewSimulatedBackend(alloc core.GenesisAlloc) *SimulatedBackend {
 	return backend
 }
 
-// Close terminates the underlying blockchain's update loop.
-func (b *SimulatedBackend) Close() error {
-	b.blockchain.Stop()
-	return nil
-}
-
 // Commit imports all the pending transactions as a single block and starts a
 // fresh new state.
 func (b *SimulatedBackend) Commit() {
diff --git a/core/error.go b/core/error.go
index d9e7e4395baa..a8ebdf88046d 100644
--- a/core/error.go
+++ b/core/error.go
@@ -65,9 +65,6 @@ var (
 	// is higher than the balance of the user's account.
 	ErrInsufficientFunds = errors.New("insufficient funds for gas * price + value")
 
-	// ErrGasOverflow is returned when calculating gas usage.
-	ErrGasOverflow = errors.New("gas overflow")
-
 	// ErrIntrinsicGas is returned if the transaction is specified to use less gas
 	// than required to start the invocation.
 	ErrIntrinsicGas = errors.New("intrinsic gas too low")
@@ -84,10 +81,6 @@ var (
 
 	// ErrGasUintOverflow is returned when calculating gas usage.
 	ErrGasUintOverflow = errors.New("gas uint64 overflow")
-
-	// ErrInsufficientIntrinsicGas is returned when the gas limit speicified in transaction
-	// is not enought to cover intrinsic gas usage.
-	ErrInsufficientIntrinsicGas = errors.New("insufficient intrinsic gas")
 )
 
 type ConsensusError struct {
diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index 93545590fdad..eaabc1a76ec6 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -17,22 +17,15 @@
 package vm
 
 import (
-	"math/big"
 	"sync/atomic"
 
 	"github.com/XinFinOrg/XDPoSChain/common"
-	"github.com/XinFinOrg/XDPoSChain/common/math"
 	"github.com/XinFinOrg/XDPoSChain/core/types"
 	"github.com/XinFinOrg/XDPoSChain/params"
 	"github.com/holiman/uint256"
 	"golang.org/x/crypto/sha3"
 )
 
-var (
-	bigZero = new(big.Int)
-	tt255   = math.BigPow(2, 255)
-)
-
 func opAdd(pc *uint64, interpreter *EVMInterpreter, scope *ScopeContext) ([]byte, error) {
 	x, y := scope.Stack.pop(), scope.Stack.peek()
 	y.Add(&x, y)
diff --git a/core/vm/logger.go b/core/vm/logger.go
index 9e82826b2e9c..e8294e3d674a 100644
--- a/core/vm/logger.go
+++ b/core/vm/logger.go
@@ -18,7 +18,6 @@ package vm
 
 import (
 	"encoding/hex"
-	"errors"
 	"fmt"
 	"io"
 	"math/big"
@@ -33,8 +32,6 @@ import (
 	"github.com/holiman/uint256"
 )
 
-var errTraceLimitReached = errors.New("the number of logs reached the specified limit")
-
 // Storage represents a contract's storage.
 type Storage map[common.Hash]common.Hash