我用simens的OPC.SimaticNet做OPC Server,vb.net和VB分别作为OPC Client, 连接Server、添加Group和Item的程序分别如下： VB Public WithEvents ServerObj As OPCServer Public WithEvents GroupObj As OPCGroup Dim ItemObj1 As OPCItem Set ServerObj = New OPCServer ServerObj.Connect "OPC.SimaticNET", "192.168.21.150" Set GroupObj = ServerObj.OPCGroups.Add("MyOPCGroup") GroupObj.IsSubscribed = True Set ItemObj1 = GroupObj.OPCItems.AddItem("S7:[S7 connection_1]MW2", 1) VB.Net Public WithEvents ServerObj As OPCSiemensDAAutomation.OPCServer Public WithEvents GroupObj As OPCSiemensDAAutomation.OPCGroup Dim ItemObj1 As OPCSiemensDAAutomation.OPCItem ServerObj = New OPCSiemensDAAutomation.OPCServer ServerObj.Connect("OPC.SimaticNET", "192.168.21.150") GroupObj=ServerObj.OPCGroups.Add("MyOPCGroup") GroupObj.IsSubscribed = True ItemObj1 = GroupObj.OPCItems.AddItem("S7:[S7 connection_1]MW2", 1) 执行VB程序没有问题，可以顺利对Item进行读写，执行vb.Net时，执行到GroupObj=ServerObj.OPCGroups.Add("MyOPCGroup")时就提示有错误：未将对象应用设置到对象的实例.