Refrigerating performance detection device and operation method thereof

A refrigerating performance detection device used for a tested unit is provided. The tested unit has a compressor and a condenser. The refrigerating performance detection device has a testing unit, an expansion valve, a refrigerant circuit and a refrigerant measurement unit. The testing unit has a detection chamber and a heater, an evaporator, an air supply structure and a chamber temperature sensor arranged in the detection chamber. The refrigerant circuit has a refrigerant circulation pipeline sequentially connected to the evaporator, the compressor, the condenser and the expansion valve. The refrigerant measurement unit is set on the refrigerant circulation pipeline and has a first temperature sensor and a first pressure sensor arranged between the evaporator and the compressor, and a second temperature sensor and a second pressure sensor arranged between the condenser and the expansion valve. The refrigerating performance detection device is therefore calculated a refrigerating information of the tested u