Abstract: The notion of an ideal refrigeration cycle based on refrigerant was established and its calculation method was developed in this paper. The ideal refrigeration cycle based on refrigerant was characterized as follows:the heat exchange process is isothermal, and the throttling process is isentropic, so the vapor compression process is composed of many isentropic processes and it is much closer to saturated process. The useful work of liquid throttling process and vapor compression process were also recovered. Based on some kinds of freon and nature working fluids, the power distribution condition, the loss of cooling capacity and cooling COP were researched in detail.