Cascaded H bridge multilevel inverter is suitable for all kinds of occasions with high voltage and high current. Carrier phase shifted sine pulse width modulation (CPS-SPWM) technology is easy to implement, and the equivalent carrier frequency is high, which has become the most widely used modulation method of cascaded multilevel inverter. Through the establishment of the mathematical model of STATCOM and the research of control strategy. On the platform of MATLAB/Simulink, STATCOM simulation of H bridge cascaded thirteen level inverters is built based on CPS-SPWM control. By observing the waveform and analyzing the output results, the compensation effect of the synchronous reactive compensator for reactive power is verified.