In order to improve the drilling accuracy of the tripping mechanism of the PCB NC drilling machine,find out the reasons that affect the drilling accuracy of the tripping mechanism,the centering device in the tripping mechanism was analyzed.The structure of the centering device was simplified,and the flexible displacement of the flexible rod in the centering device was described by the description method conforming to the flexible bending theory.The rigid-flexible coupling dynamic model of the centering device was established by using Hamilton principle,and the dynamic model was simulated and analyzed.The results show that the rigidity and damping coefficient of the elastic sleeve in the centering device have a certain influence on the displacement of the axis end of the centering rod;the greater the damping coefficient of the elastic sleeve is,the faster the attenuation of the flexible vibration amplitude is;the centering deviation has a great impact on the vibration of the centering device,the larger the deviation angle is,the greater the vibration of the shaft end of the centering rod is;increasing the compression spring can improve the rigidity of the centering rod,reduce the amplitude of the shaft end of the centering rod,and reduce the drilling vibration.