Abstract: In this paper, the center-guided hydrostatic guide rail for precision surface grinding machine is taken as the research object, and its deformation characteristics and structural rigidity under the coupling of gravity and thermal stress are studied. By constructing a finite element model, the deformation law and key parameters are analyzed by simulating the working conditions of gravity, workpiece load and ambient temperature change, combined with the deformation cloud diagram and curve of the guide rail surface of the overall and lower oil cavity, upper oil cavity and side oil cavity. The results show that the deformation of the guide rail is symmetrical, the overall deformation is mainly thermal deformation, and the deformation difference of each oil cavity guide rail surface is within a controllable range. The study verifies that the structure has good rigidity and symmetry, which can meet the engineering requirements, and provides a theoretical basis and reference for the optimal design of hydrostatic guide rails.