The feasibility of the main teaching building of Chongqing University additional lake water source heat pump during the winter heating is analyzed and the water temperature and quality of the artificial lake are determined，that the water is more serious eutrophication，and it must be purified before the water enters heat exchangers. Heat carrying capacity of lake is analyzed and hourly temperature of the lake is simulated during the winter heating operating conditions. When the average temperature is 5~8 ℃in January in Chongqing，the lake as an evaporator cycle water provide energy to heat pump constantly，assumed initial temperature of water is 13.7 ℃，hourly water temperature is simulated in January. The water temperature has dropped to 4.04 ℃ at 24 d，the evaporator surface may be frozen and cause the phenomenon of ice clogging，which will endanger the safety of heat transfer equipment，therefore，auxiliary heater must be set to ensure the main building heating.