Abstract: Organic photovoltaic technology provides an essential way for the effective utilization of solar energy. The advantages of polymer solar cells (PSCs) include low cost, light weight, easy fabrication, flexible and tunable properties. There is increasing interest in PSCs during the last few years, however, the power conversion efficiency (PCE) of PSCs far beyond practical requirements. Upon this, design and synthesis of appropriately low bandgap polymers and probing into the mechanisms become the extremely interesting topics in the field of high efficiency PSCs. In this contribution, the basic concept and the operation mechanism of PCSs, the progress of polymer materials and the problems that needs to be solved urgently in the near future were systematically reviewed.