The vacuum tube operating mechanism is the core component of the on load tap changer of the converter transformer. Its mechanical structure is relatively complex, and frequent operation often leads to plastic deformation and damage of the mechanical mechanism, resulting in converter transformer failure. Studying the dynamic simulation of the mechanical characteristics of the vacuum tube operating mechanism of the on load tap changer can compensate for the shortcomings of traditional testing methods that cannot intuitively display stress distribution, and provide a theoretical basis for the design and improvement of vacuum tube operating mechanisms. Firstly, a transient dynamic simulation model of the vacuum tube operating mechanism based on implicit nonlinear dynamics was established in ANSYS. The Von Mises yield criterion and isotropic hardening model were used to calculate the equivalent stress of the model. Secondly, the stress distribution of the operating mechanism as a whole was analyzed by finite element method. Finally, the stress distribution of the convex turntable, convex rod, support mechanism, and vacuum tube was analyzed in a targeted manner, which facilitates in-depth analysis of the working principle of the tap changer under various working conditions and helps to effectively improve the mechanical structure of the operating mechanism based on the stress distribution, and to predict and avoid possible failure modes in the design stage.