Gear is an important part for mechanical transmission.For the case of bending fatigue fracture of pinion during the transmission,the gear tooth thickness is reassigned by tangential modification.The center distance and transmission ratio unchanged,the pinion root bending stress is reduced and the root bending stress of pinion is increased by the tooth thickness reallocation,leading to bending fatigue life of each gear approximately equal.The finite element modeling of gear is carried out by using APDL language,and the bending stress analysis is carried out at a single tooth top loading and meshing gear.Compared to ordinary gear,the results validate that the gear tooth thickness reassigned by tangential modification is accuracy,and it has guidance instructive to solve tooth broke problem of pinion in engineering.