This document explains and demonstrates the gear gasher and the mechanism of the process. It is wildly applied, since the manufacturing precision can reach grade 9 to grade 8. The gear gasher composes indexable inserts, gasher body and bolts. Then the dimensions and the installation between the body and the inserts are specified and optimized, based on the cutting profile and cutting condition. The calculated model’s allowance is more even and total area allowance is smaller than the present’s. It can be used for the gasher fabrication.