The invention provides an optimal control method for promoting the efficiency of multiple photovoltaic modules in a partial blocking condition. The optimal control method comprises the following steps: step one, using a bidirectional power converter to establish an efficiency optimization structure network of the multiple photovoltaic modules in the partial blocking condition; step two, analyzing a power treatment strategy of the optimization structure network; and step three, determining an objective function and constraint conditions, and establishing an optimal linear model, so that the energy loss of the power converter is minimized on the basis of realizing power redistribution of each photovoltaic module, and the total energy efficiency is improved.