Dynamic Voltage Restorer (DVR) is a new type of power quality regulating device by which the influence of voltage fluctuation on sensitive loads can be effectively suppressed, under voltage distortion of power network it is necessary to capture the phase of positive sequence fundamental component of voltage accurately. A new decoupled double synchronous reference frame PLL (DDSRF-PLL) is used by which the phase of positive sequence fundamental component of voltage can not only be accurately detected under the condition that in the power system three phases balance sag, unbalance sag, unbalance sag and distorted, but also obtain good dynamic performance, that provide accurate lock phase angle for DVR. Thus a better compensation effect can be achieved by DVR, the simulation model of DVR with super capacitor is built in Matlab/Simulink. The correctness and effectiveness of the proposed method is verified by the simulation results.