For a certain type of photoelectric servo turntable mechanical structure and working mode,a simplified mechanical model is established,and the block diagram of the azimuth axis motor control system is outlined.MATLAB is applied to conduct simulation analysis.The resonance frequency is obtained for comparison with the measured values to verify the accuracy of the simplified mechanical model.And the relationships between the resonant results and the torsional stiffness of the steel frame,the rotational inertia of the drive assembly,and the rotational inertia of the load assembly are analyzed.