The plate heat exchanger is made up of many stamped stainless steel plates, which are combined by a guide rod and a pressing device at both ends through a sealing gasket. The number of plates in the middle can be adjusted according to the production conditions, and the hot and cold fluid is transferred in a thin wall. The sides of the board are convected to each other for heat exchange. This structural feature makes the heat exchanger not only meet the basic requirements of the heat exchange equipment for the food industry, but also has its own unique advantages. Heating, cooling and heat recovery are easily combined into one piece and completed simultaneously in one heat exchange device. As long as the heated material is used as a heat source to preheat the newly entered fluid, the operation requirements of each of the two fluids that require cooling or heating can be achieved, saving energy, and the processing equipment is compact. Therefore, in the processing of liquid foods such as dairy products, juice drinks, refreshing drinks, and beer and ice cream, plate heat exchangers are widely used for high temperature short time (HTST) and ultra high temperature (UHT) sterilization.