This paper takes an office building in Shanghai as an example and calculates the energy consumption index, economic index and environmental index of its sewage source heat pump system, fuel boiler & water chillers system and fuel boiler & sewage source heat pump system. Then entropy weight analysis hierarchy process was used to make a comprehensive evaluation of these three cold, heat source programs. The research results show that the overall performance of sewage source heat pump system is better than the other two cold, heat plans. On this basis, the paper further calculates the application scope of sewage source heat pump system. The energy-saving environmental benefits of sewage source heat pump system are much more obvious, when the distance from the sewage plant to the building does not exceed this range.