In order to improve the design level of engine, a coupled torsionalax i al nonlinear dynamic model for the shafting of engine was established considerin g random characteristics of the excitation torque on the shafts of engine and no nlinear stiffness factor. The stochastic responses of the shafting were calculat ed by the pseudoexcitation method, and the dynamic reliability of the shafting subject to random loads was analyzed using first excursion failure criterion mod el. The simulation results showed that the dynamics reliability of crankshaft su bject to stationary random excitations is higher than that subject to nonstati o nary random excitations, and the axial vibration, fire angle, intensity and tran sfer paths of the excitations have influences on the dynamic reliability of the shafting.