In order to provide reference for the selection of refrigerant for helicopter refrigeration system，firstly, take an existing air conditioning system of a helicopter as an example. According to its system and component parameters, a refrigeration system model is established in VapCyc software. Then change the type of refrigerant, the system coefficient of performance(COP)and the cooling capacity with different inlet air temperature, condenser/evaporator side air volume, and compressor speed are obtained. Under the same conditions, the COP values of R134a and R1234yf are similar and the highest two, COP of R407C is the third one, COP of R32 is similar to that of R410A and their COP values are the lowest two. The cooling capacity is R32, R410A, R407C, R134a and R1234yf from high to low. In the early stage of the research on the airborne refrigeration system, the cooling capacity of the system should be satisfied firstly. Therefore, R410A and R407C should be given priority when selecting the refrigerant of the air conditioner. Parameters such as the air volume on the side of condenser, air volume on the side of evaporator, compressor speed and other parameters have great influence on the refrigerating capacity and COP of the system, which should be carefully determined.