The static synchronous series compensator (SSSC) is compared with other compensation device, it has good characteristics of steady-state and dynamic, and choosing good control strategy is helpful to exploit the advantages of SSSC. The mathematical model of SSSC is set up in dq synchronous rotating coordinate system in this paper, and it adopts the double closed-loop control strategy and the space vector pulse width modulation technology to optimize system performance. It builds the mathematical model of SSSC in the PSCAD/EMTDC simulation environment, and it verifies the suitability and effectiveness of the control strategy.