This investigation confers the structural optimization for grinding machine pillar, using finite element method and substructure to analyze grinding machine pillar structure. This study applies the finite element analysis software Abaqus, and ANSYS to analyze the static, dynamic and optimal structure of grinding machine pillar. Substructure method for large complex structure analysis of the system is an effective method. In the process of analysis of large structure like machine pillar, adopting substructure technology to carry out finite element analysis on rib structure can reduce repeated modeling and improve the efficiency of calculation and analysis. This study verifies the reliability of substructure method. Compares with the original machine pillar, the machine pillars retain 60% stiffness with 40% weight reduction.