Abstract: The optimization of powder net-shape compacting technology and the structural design of weight reduction gear were simulated by MSC.Marc software based on the finite element method (FEM). The reliability and accuracy of the proposed FEM model were validated by the experimental results. The influences of compacting mode, compacting speed, friction coefficient, compacting temperature, and dwell time on the relative density distribution of compaction were studied by the finite element software. In the result, the combined compacting process can effectively improve the density distribution of powders as double-action pressing + warm compacting + low compacting speed + small friction coefficient + pressure maintaining. The optimal structure of weight reduction gear was carried out by the proposed FEM model, the relationship between the height-diameter ratio of spur gear and the relative density of compaction was studied, and the optimum size of weight reducing hole was determined. The results show that, the density on the thin wall of the hole can be effectively improved by using the forced friction pressing mode instead of floating pressing mode. The structural mechanics of weight reduction gear was simulated by Workbench software, the force condition on the thin wall was analyzed to reach the strength requirements of gear.