In order to analyze the performance of SCADA system communication of power grid in an effective way, this paper proposes a method of building key models and multi-scenario simulation of SCADA system communication based on OPNET Modeler. According to the actual conditions of SCADA system communication, this paper researches the modeling method of the SCADA system based on sufficient analysis on the modeling demand of SCADA system. It also establishes a network performance simulation platform that adjusts to the engineering practices of SCADA system, realizing the aim of examining the network performance through the simulation of multi-device and multi-scenario. It is a direct and effective tool that the communication modeling and simulation method of SCADA system of power grid based on OPNET to analyze on SCADA system communication network. It also provides an effective tool and practical reference for fault preview, equipment selection and network planning of SCADA system communication.