During the operation of power system, the voltage of the power grid is usually unbalanced and distorted, meanwhile the sampling signal may conclude DC component, which have a negative effect on the precision phase lock. Considering this situation, this paper introduces third-order general-integrator (TOGI) filter decoupling structure, and constructs a phase-locked loop. The function of the orthogonal signal in TOGI is analyzed, and the transformation matrix is derived to obtain the equivalent structure. It is proved that the structure can filter out the DC component and high frequency component obviously. Equivalent link is embedded in the phase locked loop (PLL) to get positive sequence voltage component in αβ coordinates, and the phase structure and the corresponding parameter are analyzed. In the end, simulation is carried out in the case of DC component, distortion and jump in the voltage signal. The simulation results show that the design of phase locked loop based on the TOGI can realize the phase lock precisely and quickly.