Abstract: The transcritical heat pump with CO₂,an environmentally friendly natural working fluid,shows great potential in high temperature heating. A CO₂ transcritical pressurization analysis model and a CO₂ transcritical heat pump analysis model have been established. Based on them,the effects of different pressurization processes on COP,outlet temperature and mass flow rate of water in gas cooler are studied. The results show that both approaches can improve the isentropic efficiency,power and outlet working fluid temperature of the compressor,and increase the outlet water temperature of the gas cooler,but decrease the COP and hot water mass flow. In general,when increasing the outlet water temperature of gas cooler,the approach of increasing the suction superheat makes power increases slightly,but the COP decreases greatly,which can increase hot water temperature in a small range. By increasing the compressor outlet pressure,the hot water temperature is higher,the controllable range is larger,and COP has a smaller decline.