The simulation turntable is a high precision and semi-physical simulation installation. In order to meet high precision of turntable, the precision prescribed in all sets of axes of turntable is required during manufacturing process and assembly. Based on assembly process of three-axis simulation turntable, the detachable structure of U frame is designed. Components of the frame are formed by bolted joints. So the strength and stiffness of the U frame with bolted joints must meet initial design requirements, simple and reliable finite element simulation method of bolted joints is applied based on ANSYS software in the paper. The connection of screw threat pair is simulated by nonlinear elastic contact mode, and the preload to bolts is loaded though pretension element of ANSYS software. The numerical analysis is performed to confirm that the detachable structural U frame with bolted joints is satisfied with structural requirement and the strength of U frame is influenced by the pre-tightening force of bolt at the extent.