Energy is most important issue in the world now because the chemical energy (oil, natural gas, coal et al) is on the edge of depleting. Many Countries are now paying attention to the use of sun power. Photovoltaic device is the most important way to make use of sun energy. Organic solar cell is one promising kind of photovoltaic device, though it’s low power conversion efficiency hampers its commercialization. This paper briefly reviewed two ways to improve the power conversion efficiency of organic solar cells and pointed out the unsolved problems.