The invention discloses a cold and heat balance device for a test room of a heat pump water heater, which includes a compressor, a three-way regulating valve A, a heating heat exchanger, a cooling heat exchanger, a three-way regulating valve B, an economizer, and a gas-liquid separation device. The water storage tank, the water channel of the cold water evaporator and the water channel of the hot water condenser are connected through pipe groups to form a water circulation system; the water channel of the cold water evaporator Refrigerant channel, refrigerant channel of hot water condenser, compressor, three-way regulating valve A, heating heat exchanger, cooling heat exchanger, three-way regulating valve B, economizer, gas-liquid separator, liquid receiver It communicates with the filter through another pipe group to form a heat pump circulation system. The present invention has the advantages of: adopting cold and heat balance, transfer, and storage technologies, using little electric energy as a drive to meet the temperature requirements of the test room -25°C to 50°C, replacing the input of steam and electric heating equipment, low investment cost, The installation and operation are simple, and the system is highly efficient and energy-saving.