The servo valve is the core control element of hydraulic cylinder control system (HCCS), the computer system implemented the closed-loop control is the main control mechanism of HCCS and the D791 servo valve itself used for rolling mill is the control valve with closed-loop control. In the paper, the working principles of MOOG D791 servo valve are introduced as well as the control characteristics of its flow and its dynamic properties are analyzed. The feedback signals of spool displacement for servo valve could be seen with the simulated program as well as the superiority and inferiority for its working performances could be judged through the following features curve of feedback values and set values in the whole motion process of servo valve.

servo system  /  HCCS  /  servo valve  /  analysis of flow control