Aimed at the problem of number and position to install center frame as grinding slender shaft, depending on experiments and compensate on cutting at present, the infinite analysis and optimization method was put forward. ANSYS Workbench software was used to select the center frame setting scheme that met the machining requirements.The load and constraints were carried out to locate mode of double centers.The optimized mathematical model was established to optimize the relieving amount,and optimizing method fitted to ANSYS Workbench was put forward. Based on the 900 mm long, 30 mm optical parametric modeling and analysis of the optimization,the changing rule of the relieving amount when there was no center frame was analyzed, and the position scheme when the relieving amount was optimal under one center frame and two center frames was also analyzed,and the result was further verified. For considering dynamic stiffness, the first six modes and modal frequencies of the three schemes were obtained. The experimental results show that the analysis results are in accordance with practical process. It is proved that the method is feasible,which can provide a kind of feasible method for setting center frame on machining slender shaft.