Existing research on the analysis heat pump operation generally focuses on the efficiency of doing work while ignores heat loss in the transfer process. Hence, heat pumps are often studied based on theory of minimum entropy production. However, this theory is rarely applied to optimizing heat transfer process without heat work conversion. Taking the air source heat pump hot water supply system of a hotel building as an example, this paper simulates the heat production, power and coefficient of performance of the air source heat pump during operation based on the theory of entransy and entransy dissipation proposed by Professor Zengyuan Guo. The findings show that heat pump operates best at inlet water temperatures of 293K and 298K, with a coefficient of performance of 4.8. In the water at a temperature of 298K, water temperature can be adjusted by the function of heating capacity between 30 kW and 40 kW to minimize the system's entransy dissipation, where the system's unit power consumption reaches its minimum at 9 kW, corresponding to an entransy dissipation of 245.4 kJ•K. This study provides a good research idea to optimize the thermal power conversion process using the theory of entransy and entransy dissipation.