In order to deal with the problem of the traditional phase-locked loop (PLL), such as it can only get the frequency and does not consider the phase of grid voltage, the PLL control is inaccurate, leading to poor control performance of the whole system and so on. This paper proposes a control strategy without PLL which is applicable to CSC-STATCOM, transforms the coordinates in three-phase grid voltage, and gets the synchronous rotation angle according to the relationship of the coordinate systems. This control strategy can get the precise frequency and phase of grid voltage in time. The control strategy of this system is introduced in detail, and a model of the system is built in Matlab/Simulink. The effectiveness of this control strategy is verified by simulations performed in Simulink, and the simulation results indicate that this control strategy can improve detection accuracy of the system, and can speed up the dynamic response of the system.