Based on the analysis of the defects induced in the process of forming and drilling of composite components,the main factors influencing the distribution of assembly-induced-stress and the influence law are investigated from three aspects, including the forming quality of components, the machining quality and fitting quality of connection hole. It indicates that the assembly-induced-stress of connection zone can reach 537MPa as assembly gap is 1.0mm while it is over 300MPa with 1° perpendicularity error. Moreover, when the coaxiality error of connecting holes is 0.03mm, the assembly-induced-stress exceeds 443MPa. Large assembly-induced-stress results in the propagation of the defects induced in forming and drilling and secondary damage, thus severely diminishing the assembly quality. Therefore, ef-fective inhibition strategies for the initiation and propagation of secondary damage are put forward from the two aspects of reducing initial damage with reasonable design of structure and layers, optimization of forming process and drilling parameters; and simultaneously declining assembly-induced-stress by automated assembly technology, fixture device optimization, reasonable arrangement of assembly process and application of shimming compensation process, which provide theoretical approaches and technical support for high-quality and precise assembling of large-scale composite bearing components.