The parallel kinematic machines have broad application prospects in the manufacturing industry. Good dynamic characteristics are needed for the structure, which has direct influence on working efficiency, stability and reliability. ANSYS software analysis of their dynamic characteristics is accurate and easy, and can quickly modify the design fault and reduce design cost. In this paper Pro/Engineer is used to draw the solid model of PKM and assembly each part to constitute a system. At last the whole system is imported into ANSYS. The finite element model is established with the simplified model and element equivalent simulation, and modal analysis is conducted using model vibration theory and finite element theory. After the vibration deformation analysis of whole system, the weak parts, i.e. each bearing joint and the power transmission chains, are identified. The weak parts can then be enforced to improve the dynamic characteristics of the whole system.