Aiming at the surge problem of magnetic suspension fluid machinery， a surge control strategy based on mass flow is adopted according to the fluctuation of mass flow and pressure rise in the surge state of fluid machinery system. Specifically， the surge controller is used to calculate the axial adjustment clearance of the impeller. It is input into the closed-loop control system of the axial magnetic bearing as the reference signal of the suspension position， to change the axial position of the magnetic suspension fluid mechanical rotor under the action of the axial magnetic bearing system. The tip clearance of the impeller is changed to realize the active control of surge. The simulation results show that when surge control is applied， the stable operation range of fluid machinery can be extended from 15.5% throttle valve opening under uncontrolled control to 14% under surge control. The surge frequency is identified by simulating excitation， and the influence of control parameters in PID controller on surge control performance is studied.