Abstract: High power STATCOM can provide a large amount of reactive power for power transmission, however, its control system is highly nonlinear. In order to realize linear control reactive power of STATCOM, a new type is proposed based on MLCR-CSC. The STATCOM working principle is introduced, and the direct current control strategy is designed with double closed loop control system. The simulation results show that MLCR-CSC harmonic content is lower than 4%, and six zero current pulse realized large zero current switching. STATCOM satisfied the demand of reactive power in power grid and gave a quick responds during asymmetric fault.