A new positive and negative sequence component separation method was proposed to solve the problem that the traditional PhaseLocked Loop (PLL) can not obtain the phase accurately by using the conventional Software PLL (SPLL) under the condition of grid voltage unbalance. It used the phase Sequence Decoupling Resonant (SDR) controller to better perform the highorder harmonic filtering effect and the Delayed signal cancellation (DSC) have characteristics that could filter out of the specific harmonics, combine SDR and the DSC to achieve a good positive and negative sequence Component separation effect. Finally, the simulation results of MATLAB/Simulink showed that the proposed method was feasible and effective.