A pressure control system is designed to control the pressure inside the cylinder via the valve’s switching and opening degree in the LED wafer pasting process. The method of multi-target and multi-step decision and control is proposed, which can control the piston’s motion and pressure. According to the displacement and pressure on the piston, the logic decision method is used to select the valve that needs to be controlled. According to the error and error change rate between planned and actual measured pressure, the fuzzy adaptive PID control method can be used to purposeful control valve’s opening degree. By using the method of semi-tensor product, fuzzy reasoning can be transformed into a matrix form, which can greatly simplify the computation, and improve the calculation speed and the control precision.