The invention belongs to the technical field of transcritical carbon dioxide (CO2) refrigeration heat pumps. A refrigeration heat pump unit of a CO2 transcritical cycle comprises a CO2 refrigerant compressor, a gas cooler, a regenerator, a throttle valve I, a gas-liquid separator, a throttle valve II, an evaporator, a controller, a pressure sensor, a temperature sensor and a superheat temperature sensor. All parts are connected through pipelines to form a closed system. The controller controls opening degrees of the throttle valve I and the throttle valve II according to detected refrigerant pressure in the gas cooler, detected refrigerant temperature of an outlet of the gas cooler, refrigerant superheat degree of an outlet of the evaporator and the highest cooling pressure Pg of system operation, and the unit is enabled to be operated under high cycling efficiency. The refrigeration heat pump unit of the CO2 transcritical cycle and a control method of the refrigeration heat pump unit of the CO2 transcritical cycle have the advantages that when environment temperature or environment temperature of a cooled department changes, the controller can adjust the unit and enable the unit to be operated under the high cycling efficiency, and the method is simple, easy to achieve, reliable and stable.