Abstract: A complete gear train of a reduction gearbox is the object of finite elementstress analysis. One of the basic segments of the complete gear train is taken as the computational model in the light of the cyclic symmetry of the gear train, meanwhile the contact transmission forces between the corresponding meshed teeth are considered in the analysis of the model. For simplicity the corresponding meshed lines are used instead of the actual contact surfaces. Both torque and centrifugal loads are involved in the analysis. The stresses in all the parts of a complete gear train can be determined by one analysis. The computed results show that the contact force on a meshed tooth is correlative not only to the length of the meshed line, but also to its position, and, moreover, the neglect of the stress resulted from centrifugal load is inappropriate to a high speed gear train.