The corrosion morphology and products of the defect morphology of the used injector were analyzed, and the injector model with defects was established based on the characterization method of the defect equivalent area of pipe parts based on the Modified B31G standard. The influence of the change of parameters such as the defect equivalent area, depth and angle on the residual strength of the injector pipe parts was explored by using the finite element technology. The results show that the increase of defect equivalent area can improve the stress concentration in the defect area, but has little effect on the structural strength. The residual strength of injection distributor pipe parts is mainly affected by the defect depth, and the growth rate of stress peak increases with the increase of defect depth. When the defect depth is the same, the change of defect angle has little effect on the pipe strength.