The rigid-flexible coupling model of axle gear case in tunnel traction locomotive which included the flexible axle and case body was established using Romax, Inventor and Hypermesh software. Tooth profile modification, gear-tooth fatigue strength, bearing life, and the static strength and modal of case body were calculated and analyzed by applying load spectrum to the rigid-flexible coupling model, in which the effects of the flexible deflection, bearing clearance and misalignments were detected and considered. The calculation results and actual practice showed that the rigid-flexible coupling model of axle gear case could be used for developing the product in the design work.