The±50 Mvar static synchronous compensator（STATCOM） installed at Shanghai Xijiao substation greatly improved the voltage stability of Shanghai Power Grid， and remedied the defects of the current var compensation devices that cannot dynamically support system voltage. The measurement and control system is one of the core parts of STATCOM. It produces and controls the driving switching device pulse to control the device operation by measurement and calculation， and completes each function that STATCOM needs to complete. This paper introduces the control system， the construction of the monitoring and fault diagnostic system and the design of the communication system as well. The realization mode of the measurement and control system is also highlighted. Tests results confirmed that all performance requirements are met.