Considering the random output of photovoltaic power generation in the process of generating electricity, a Super-Twisting sliding mode control algorithm for Maximum Power Point Tracking (MPPT) is proposed which is based on Boost circuit. By selecting appropriate sliding mode surface, the higher-order discrete control rate can be obtained, which leads to continuous control variables in time. Thus a chattering-free sliding mode converter is designed to achieve the MPPT, meanwhile, the influence of chattering is effectively eliminated. In order to verify the superiorities of the algorithm, a photovoltaic power generation system model is built in Matlab/Simulink to carry out simulation experiments. Compared with the traditional control algorithm, the results reveal that the proposed method can quickly achieve the MPPT under the disturbances of variable light and temperature, which exhibits strong robustness simultaneously. This work is supported by National Natural Science Foundation of China (No. 51477070) and PAPD (No. 20116).