When the grid voltage contains multiple harmonics and DC voltages, the decoupled double synchronous reference frame phase-locked loop (DDSRF-PLL) has a large deviation from the frequency and phase locking of the grid voltage.A novel PLL proposed in this paper adds a new type of orthogonal signal generator (SOGI-QSG) to filter out harmonics and DC voltage before decoupling the positive and negative sequence of dq signals, and provide DDSRF-PLL with a steady alpha beta signal,which improves the ability of the PLL to suppress harmonics and DC voltages. Matlab/Simulink simulation study of the PLL and comparison with DDSRF-PLL and DDSRF-PLL adding traditional orthogonal signal generator verify that the PLL can filter out the harmonics and DC voltage in the grid voltage containing multiple harmonics and DC voltage, which effect of frequency and phase lock is better and can effectively improve the stability and reliability of the system.