Abstract: In order to solve the problem of machining stability and accuracy of the large diameter Fresnel lens mold processing machine,the static and dynamic analysis of the whole machine was conducted based on ANSYS Workbeach software,providing reference for optimizing the design of machine tool structure.First of all,through the static analysis,the weak link of large diameter Fresnel lens mold processing machine was obtained; Then,modal shape of the first six order was acquired by modal analysis method,and the relationship between the above structure modal frequencies and mode shapes was researched. The results show that beam stability is low and weak,and the beam front inner X stiffened plate needs to be strengthened. The maximum displacement occurred in the beam position,and the deformation mainly occurred in the anchor,so it is need to improve the quantity and layout of the anchor. The improved scheme is that keeping the beam reinforcement plate thickness constant,changing the inside stiffened plate composed of ten-vertical structure into a V-shaped structure. The body paragraph need to be increased three anchors into isometric arrangement to provide support for strengthening stiffness of the machine tool.