As a new energy-saving product, the plate heat exchanger unit lacks effective and clear means for how to detect whether the plate heat exchanger unit is qualified and whether it meets the design requirements for on-site operation. In the actual operation of the plate heat exchanger unit, it needs to test a lot of data: the logarithmic average temperature difference of the plate heat exchanger, the operating point of the pump, the resistance value of the primary and secondary sides of the heat exchange unit, and heat exchange flow of the primary and secondary sides of the unit. The heat exchanger unit does not have its own design ideas and theoretical basis. The plate heat exchanger, water pump and control system are composed of three cores. Plate heat exchanger and water pump are the core of the design of the plate heat exchanger unit. The current design of the plate heat exchanger unit is just to stack these equipment under the original design ideas, and the plate heat exchanger unit is not designed as a whole system. Only based on the design theory of the plate heat exchanger unit, it can be further developed.