Wide area monitoring system（WAMS） has a wide application in power system dynamic analysis and control. To improve the stability and reliability of WAMS， a WAMS spot test method is proposed. The content of WAMS spot test can be determined based on its structure. A synchronous phase control instrument is also developed to facilitate the synchronous simulation and control system with synchronous test control center. By conducting the single node and multi node synchronous test via the synchronous simulation and control system， the steady-state and transient performance， the application function of WAMS can be evaluated. Finally， the feasibility and practicability of the method is proved by spot test and MATLAB simulation.