To study the influence of the input time delay of the controller on the stability and dynamic performance of the active magnetic bearing-rotor system， an equivalent model of the active magnetic bearing-rotor control system with input time delay is established， and the approximate value for the critical delay of the active magnetic bearing-rotor system is obtained by analyzing the existing conditions of Hopf bifurcation in the system. The influence of control parameters on system stability is analyzed by MATLAB/Simulink simulation， and the existence of Hopf bifurcation is further verified. The influence of input time delay on the ability of closed-loop systems to suppress external interference is explored from the perspective of system amplitude-frequency characteristics and phase frequency characteristics. Finally， experimental verification is carried out on the simulation content. The results show that the increase of the input time delay will leads to the Hopf bifurcation of the system. The peaking phenomenon of the amplitude-frequency response curve of the closed-loop system is aggravated， and the stability of the system is reduced. For PID controller， increasing the proportional gain and decreasing the differential gain can amplify the influence of input delay on system stability.