Aimed at the problem that the conventional grid-connected PV inverters do not take into account the dynamic and steady-state performances when the surrounding environment changes, an optimal control method of combined reaching law sliding mode inverter based on grey wolf optimization (GWO) algorithm is proposed. Firstly, the method uses the integral sliding mode to track the DC bus voltage in the outer loop of the control system to keep it constant. Then, to reach the grid-connected control of the PV inverter, the sliding mode switching surface function with error integral term is established by the d and q axis current in the current inner loop to track the active power and reactive power respectively. Furthermore, in order to reduce the chattering of the system effectively and stabilize the system on the sliding mode, the combination reaching law of exponential reaching law and variable speed reaching law is introduced into the inner and outer loop control. Finally, to improve the accuracy of control system, the global optimization of sliding mode surface parameters is carried out with the iterative optimization ability of grey wolf optimization. The simulation results show that the proposed control method enable fast and exactly track the grid-connected currents, thus, the stability and anti-interference ability of the grid-connected photovoltaic system is improved as well.