Evaporation pressure control method applied to refrigeration system and the refrigeration system

An evaporating pressure control method applied to a refrigeration system, and the refrigeration system includes a compressor, a condenser, an expansion valve, an evaporator, and a controller. The control method includes following steps. The controller continuously records a first temperature of the evaporator, a second temperature of the expansion valve, and a third temperature of the refrigeration system according to a time series. The controller performs calculations based on plural temperature differences and plural second temperatures. When the controller determines that the compressor is operating in a low load state, the controller continuously increases the evaporation pressure of the evaporator.