Abstract: In order to realize the rotor height and horizontal equilibrium control, and safety protection, he hydraulic system and controller of the composting aerator suspensions were studied. The research has used the change structure and the PID control, obtained the control of high precision in the rotor level. The model was built by LQG control of the rotor system and the control law of position control was inferred by linearity random best control. The changing law of rotor parameters under different signals was known by Matlab simulation. Based on work data which supposed in advance, the rotor height was controlled real-time. This control policy can eliminate the oscillatory phenomena effectively which caused by the friction force, and achieve the control objective smoothly. The hydro-pneumatic suspension can improve the property of the rotor height control with the LQG control.