Through the analysis of the drilling error of the PCB numerical control drilling down mechanism,the main reasons affecting the processing accuracy of multilayer PCB boards were found out,and the rigid flexible coupling dynamic characteristics during the spindle systems drilling process were studied.The coupling between the flexible self-centering spindle in the self-aligning coupling and other rigid components were fully considered,and the dynamic equation of the spindle system of the drilling down mechanism was established using Hamiltons principle and modal analysis method.The dynamic response of the electric spindle during the drilling process of the drilling down mechanism was obtained through simulation.The results show that the installation error of the main spindle system of the drilling mechanism,the stiffness of the centering shaft,and the damping of the air bearing supporting the electric spindle have a certain impact on the eccentricity error of the drilling and the flexible vibration during drilling.