In order to reveal the power split characteristics of the spiral bevel gear train,first,a mechanical struc-ture model for the system is constructed according to the closed- loop characteristics of the system power flow.Then,the moment equilibrium equations as well as the deformation compatibility equations describing the relationship be-tween the moment and the normal deformation of tooth surface are derived.Finally,the load moment of each gear pair and the moment distribution general formula of the second and the fourth roads which directly reflects the power split situation of the system,are obtained.It is found that the measured tooth strain of the system coincides with the theoretical calculation results.Thus,the proposed method proves to be feasible and effective.