During the working process, the structural system, including bevel gear, shaft, and bearing, located in the front journal of the high pressure compressor of the aeroengine rotor is affected by various loads such as assembly load, centrifugal load, temperature load, and meshing excitation, and it leads to different modes of interface damage, for example, wear, slip, and fatigue. With the increase number of working cycles, different interface damage modes affect each other and damage gradually accumulates, which leads to the degradation of the mechanical properties of each component. Finally, the function of the weakest component is lost, resulting in the failure of the structural system. Consequently, the comprehensive influence of multiple failure forms caused by interface damage at different positions results in the failure of the structural system, where the damage position and the failure position are different, and the final failure form is uncertain. In this paper, a damage accumulation mechanical model considering multimode damage interaction is established for bevel gear, shaft and bearing structure system. And the damage-failure mechanical process of the structural system and its key influencing factors under complex environment loads are studied. The results showed that the failure forms of the structural system were closely related to the assembly and load characteristic parameters of the components. Therefore, considering the randomness of the initial assembly state and environment loads, the damage accumulation mechanical process and the final failure forms of the structural system have significant uncertainty.