Abstract: In order to analyze the influence of signal clearance delay on the system stability,and to offer direction to control parameter modulation during experiment,the influence of delay of gas clearance on control parameters' stable region is analyzed.Because of the signal clearance delay,the lower limit of the stable region of the position feedback control parameter is increased,the upper limit of the stable region of the derivative feedback control parameter is decreased,the stable region of the control parameters is reduced,and the dynamic performance is worsened at the same time.The conclusion is proved through simulation.