To solve the disturbance problem of single-phase grid-connected photovoltaic inverters in island mode, the traditional control strategy based on internal model principle can realize no static error control, but it is insufficient to suppress the disturbance. The SC-PID control strategy based on virtual orthogonal method and synchronous rotating coordinate system is proposed in this paper. By defining system dynamics and internal and external uncertainties as summation perturbations, the unknown function and external perturbations are combined into summation perturbations for second-order non-affine nonlinear uncertain systems, and the system is simplified to linear uncertain affine system. On this basis, the SC-PID control law model and its tuning rules are designed. The simulation results show that the proposed method not only improves the response speed and control precision of the system, but also enhances the robustness of the system and the ability to suppress the disturbance.