PID control method of fuel cell system

The invention discloses a PID control method of a fuel cell system. The PID control method comprises: constructing a theoretical database of a fuel cell, the theoretical database comprising power parameters and cooling liquid temperature parameters, hydrogen flow parameters and air flow parameters corresponding to the power parameters; obtaining a theoretical parameter value of the fuel cell and an actual parameter value corresponding to the theoretical parameter value, and calculating a deviation value between the actual parameter value and the theoretical parameter value, the theoretical parameter value being any one of a cooling liquid temperature value, a hydrogen flow value and an air flow value; inputting the deviation value into a preset PID control algorithm to calculate the control quantity of the fuel cell; and controlling a corresponding execution mechanism to adjust the temperature, the hydrogen flow or the air flow of the cooling liquid input into the fuel cell according to the control quantity,