Abstract: Analyzed with applicable FEA software are the stress-strain distribution and the residual strength of the casings with groove corrosive defects of different sizes under the internal pressure.And the regularity of the influence by the groove corrosive defect on the casing strength is predicted by means of the elastic-plastic finite element method(FEM).The results show that given that the groove corrosive defect size is the same,the smaller the casing OD,and the thinner the casing thickness are,the bigger equivalent stress peak value of the casing shall be;and compared with pipe OD,the pipe thickness produces a more obvious effect on the residual strength of the casing.The residual strength of the casing with groove corrosive defect is evaluated,based on which,it is concluded that the deeper groove is,the lower the residual strength shall be,and the pipe diameter and wall thickness have a more significant effect on the residual strength.