Topology optimization with OptiStruct method has been conducted on a gear respecting constraints and correct load . The Results demonstrated a new and peculiar design. Considering that This desing is not the definitive desing. The component must be redesign with CAD software to reach the detailed and flawless gear . by taking into consideration of all these factors we have gained approximately 40% reduction in weight by keeping the safty factor greater than 1.2 .of light weight gear