The test platform of hydraulic motor was studied as the main subject, and a kind of mounting structure applicable to various types of motor was designed. By using the software ANSYS Workbench, the finite element model (FEM) of structure was established. By statics and modal analysis of the model, the structural statics behavior, the inherent frequency and the mode of vibration under bolt pretightening force and torque load were obtained. Through the central composite design experiment and response surface analysis, the influence rules of parameters such as the thicknesses of support and rib board, bolt pretightening force and torque on the structural strength, stiffness and the inherent frequency are summarized, and the reasonable design parameters are found to complete the structure optimization design.