The dynamic performance of the worktable has a great influence on machining quality. In order to improve the machining precision, the paper conducts the analysis and research on the workability of a numerical control engine bed rotary worktable from a domestic machine tool factory，and discusses the influence of dynamic characteristics of rotary worktable on the precision of numerical control processing. Firstly Ansys finite element analysis was employed to analyze and simulate the modality and natural frequency of the numerical control rotary worktable under various steps. And then, a vibration test on the numerical control rotary worktable to confirm accuracy of the simulation parameters was carried on. Finally a contrast was made between the theoretical analysis and the experimental analysis to point out the resonance frequency and the distortion of the rotary worktable. Also the influence of numerical control rotary worktable on the numerical control processing was discussed.