diff --git a/Nvr.go b/Nvr.go
index ddd6fee..75f1151 100644
--- a/Nvr.go
+++ b/Nvr.go
@@ -7,6 +7,7 @@ package HikSDK
 */
 import "C"
 import (
+	"errors"
 	"gitea.com/kunmeng/HikNetSDKPkg/Core"
 	"time"
 	"unsafe"
@@ -29,6 +30,9 @@ func NewNvr(Ip string, Port int, Username, Password string) (*Nvr, error) {
 }
 
 func (this *Nvr) GetTimeZone() (int, error) {
+	if this == nil {
+		return 0, errors.New("Nvr is nil")
+	}
 	var data Core.NET_DVR_NETAPPCFG
 	var dataPtr = unsafe.Pointer(data.GetCPtr())
 	err := Core.GetDVRConfig(this.userId, 222, 0, dataPtr, Core.DWORD(unsafe.Sizeof(data.GetC())))
@@ -41,7 +45,9 @@ func (this *Nvr) GetTimeZone() (int, error) {
 }
 
 func (this *Nvr) CheckTimeRegionWithMonth(Year, Month, Channel uint16) ([]uint8, error) {
-
+	if this == nil {
+		return nil, errors.New("Nvr is nil")
+	}
 	//	//// 查当月
 	var struSearchParam Core.NET_DVR_MRD_SEARCH_PARAM
 	struSearchParam.DwSize = Core.DWORD(unsafe.Sizeof(struSearchParam.GetC()))
@@ -72,6 +78,9 @@ func (this *Nvr) CheckTimeRegionWithMonth(Year, Month, Channel uint16) ([]uint8,
 }
 
 func (this *Nvr) CheckTimeRegionWithDay(Year, Month, Day, Channel uint16) ([]TimeRange, error) {
+	if this == nil {
+		return nil, errors.New("Nvr is nil")
+	}
 	var Data Core.NET_DVR_FILECOND
 	Data.DwFileType = 0xff
 	Data.DwIsLocked = 0xff
@@ -163,6 +172,9 @@ func (this *Nvr) CheckTimeRegionWithDay(Year, Month, Day, Channel uint16) ([]Tim
 	return res, nil
 }
 func (this *Nvr) Logout() error {
+	if this == nil {
+		return errors.New("Nvr is nil")
+	}
 	return Core.Logout(this.userId)
 }