Based on requirement of new invented ESD measurement system, the automatic control system of pressure was designed to automatically control the pressure of experimental box. The proposed system uses STM32 MCU as its core. MCU, after received feedback signal of sensor, controls on-off state of solenoid valve with applying PID algorithm to output PWM impulse. Pressure of experimental box can set desire value and keep it stable. The design provides compensation to remove deficiency in original pressure control process, runs faster, more accurate and convenient operation than that before. The design provides accurate pressure environment in the experimental box of the new ESD measurement system.