At present, there is less research on the effect of STATCOM on commutation failure with many factors and the detailed control system model. Based on the actual engineering parameters, the PSCAD/EMTDC model of HVDC transmission system with STATCOM is established, and the DC transmission control system is built according to the predictive control system. Considering the factors including AC electrical cycle characteristics, STATCOM rated capacity and fault type, and considering the interaction of STATCOM and HVDC transmission module, the commutation failure immunity factor, commutation failure time duration and recovery performance analysis index are used to evaluate the role of STATCOM. Research shows that: in a period of different time, the ability of STATCOM can effectively enhance the system against commutation failure, shorten commutation failure duration and recovery time, and shorten the length were 0-3ms and 7-11ms. Increasing the STATCOM rated capacity can further play its positive role; Compared with the single phase commutation failure, the STATCOM has a better effect on the continuous commutation failure, but for the more severe metal grounding fault, the improvement effect is not obvious because of its capacity limit. The difference of STATCOM capacity will affect the prediction of commutation failure and the output of low voltage current limiter. The research has certain reference function to the STATCOM selection and optimization in HVDC project, in the future.