The impacts of temperature, flow and lift of cooling water on the energy efficiency ratio of surface water source heat pump system were analyzed. The cooling load of air condition and parameters of cold water were set as control objectives, and the analytical model of energy efficiency ratio of cooling water system including energy consumption of water source heat pump was proposed. The running energy efficiency ratios of two types of surface water source heat pump systems (direct heat transfer of surface water flowing into chilling water unit directly, and indirect heat transfer through plate heat exchanger) were analyzed by using this model. The results show that the impact of change of cooling water temperature on energy efficiency ratio is bigger than change of lift of cooling water system. In partial load condition, the energy efficiency ratio of chilling water unit and cooling water system reaches the maximum when the temperature of cooling water is 23~24°C.