The crossbeam ribs of the shaped stone turning milling center was designed with the help of topology optimization method.Through in-depth analysis of SIMP topology optimization,the effect of penalty factor on topological structure was discussed,before and after iterative formulae of design variable were derived.This mathematical thought was achieved by MATLAB,and was applied to the distribution of longitudinal cross sectional ribs of turning milling machining center cross beam.Then the three-dimensional model of cross beam was established according to the cross-section shape.Entity designed and manufactured based on this model was applied to the cross beam of shaped stone turning milling CNC machining centers HTM50200.Finite element analysis and modal experiments show that the dynamic characteristic of the beam is good,which indicates the validity and reliability of the optimization design method.It provides a new idea for structural optimization.