Grid photovoltaic system’s inverter, grid device and other power electronics device consume a large quantity of reactive power, the distribution system load mostly is perceptual, it must also consume reactive power. This will make big interference interconnection of photovoltaic system after the transient voltage stability serious test. Therefore, the study grid photovoltaic system transient voltage stability is of great significance. This paper introduces the transient voltage stability of research contents, such as transient voltage stability of factors, stability criterion, the simulation calculation, and puts forward prevention transient voltage instability accident measures, and analyzes system transient voltage stability mechanism.