Although the traditional phase locked loop (PLL) based on double second-order generalized integrator (DSOGI) can finish the phase-lock in the case of three-phase imbalance or harmonics, the quadrature generator of the second-order generalized integrator is difficult to completely filter out all the harmonics. Aiming at the difficulty of phase lock when three-phase imbalance and grid harmonic pollution, this paper proposed a fast phase synchronization scheme. Firstly, the DSOGI can achieve quadrature signal generation, and filter out high-order harmonics, so that it can obtain the positive-sequence component which may contain low-order harmonics, and ensure accurate phase lock when the three-phase unbalance. In the dq synchronous rotation coordinate system, the delay signal cancellation (DSC) scheme was used to filter out the lower even harmonics, thereby avoiding the problem of poor dynamic response when applying low-pass filter(LPF). Finally, the q-axis component was controlled to 0 by PI regulation to realize the fast extraction of synchronous signal. The simulation results built in Matlab/Simulink verified that the proposed fast synchronous phase scheme can quickly phase lock when the power grid is unbalanced and exists harmonic pollution.