The diaphragm cylinder diameter of intelligent self-operated pressure reducing valve（intelligent pressure reducing valve for short）have important influence on sealing performance of control unit，which affects the valve performance parameters such as pressure variation range，service life，power and etc.This paper presented a method to optimize the diaphragm cylinder diameter of intelligent pressure reducing valve，including building the pressure correlation theoretical model according to static equilibrium equation，getting the raw data by fluid experiment and high accuracy sampling，building the actual mathematical model by linear regressive，and optimizing the diaphragm cylinder diameter by minimal extreme optimization model with constraint condition.The results show that under the optimization dimension，the sum of pressure difference reduces by 30.6%，the limitation value of the maximal pressure difference reduces by 7.7%，and the limitation value of the minimal pressure difference reduces by 39.6%，which are beneficial for reducing the control system leakage.The pressure correlation model and optimization model offer a good reference for the design of intelligent pressure reducing valve.