To explore the influencing factors of green efficiency value of power company and analyze the feasibility of constructing green efficiency index system in power industry, ten influential power generation companies were selected as the research objects. The green efficiency of the ten power companies was measured through the DEA(data envelopment analysis)model, and the factors affecting the green efficiency were analyzed. By comparing the green efficiency horizontally and vertically, it is found that the influence factor of the green efficiency includes the installed capacity and the fuel cost. The green efficiency of power companies is affected by the size of the company and some environmental related policies. The construction of the green index system of the electric power industry has a certain feasibility.