Abstract: Due to the influence of air leakage and seasonal temperature change,when the air cushion surge chamber(ACSC)adopts the constant P0V0 value operation control mode( "P0V0 mode"),it still needs to carry out makeup and exhaust operation to ensure the normal and stable operation of the power station.Based on the analysis on the characteristics of the commonly used "P0V0 mode",this paper put forward the optimization determination method of the operation control constant in the ACSC,analyzed the steady-state and dynamic change range and interrelation of the control parameters of the air chamber,put forward the requirements of air replenishment and exhaust,as well as the setting method and principle of the controlling threshold.Aiming at the problem of dynamic signal interference threshold setting,four kinds of operation state identification methods were put forward to improve the threshold setting obviously,which could provide systematic and standardized control threshold setting ideas and methods for the operation control of ACSC.