Abstract: When sub-synchronous oscillation (SSO) occurs in the power grid, the working performance of the photovoltaic (PV) inverter will be disturbed, affecting the stability of the power generation system. In response to this issue, this article first analyzes the impact of phase disturbance in the output of the phase-locked loop (PLL) on the coordinate transformation process; a mathematical model of PV grid-connected inverter is then established to take into account the phase disturbance; the mechanism of the disturbance caused by SSO of power grid is sorted out; and the disturbance is divided into physical disturbance and error disturbance. Then, an improved PLL is designed to eliminate the influence of the error perturbation caused by the phase on the PV system. Next, a comparative analysis is conducted on the suppression effects under different targets, and the key factor affecting the controller due to the oscillation voltage characteristics are identified. According to the above research, a power oscillation suppression strategy of PV power generation system based on adaptive quasi-resonant controller is proposed. Finally, the effectiveness of the proposed control strategy is verified by setting up an experimental platform.