Polymer solar cells have attracted wide attention due to their comprehensive advantages of environmental protection, low energy consumption, light weight, low cost, flexibility, solution processing and large-area printing. The active layer is the most important component of PSC，and the adjustment and optimization of its morphology determine the final device performance. Therefore, it is necessary to systematically organize and analyze the active layer optimization process. In this paper, the latest research progress of the application of reactive layer post-treatment technology in PSC is reviewed，including the thermal annealing, solvent vapor annealing, combination of thermal annealing and solvent vapor annealing, addition of the auxiliary layer and polar solvent-assisted post-treatment. In addition, the reasons for improving the device performance and the mechanism of optimizing the morphology of the active layer are analyzed and summarized, which provide a theoretical basis for the performance optimization research and industrial development of PSC.