Abstract: In order to determine the influence of corrosion defect on the residual strength and bearing capacity of in-service pipeline conveniently and accurately, finite element software ANSYS is applied to simulate two kinds of defect models, which is based on the elastic limit guidelines of pipeline with defects, and gets the Mises stresses of corrosion area under different defect sizes. According to the calculation results and considering the corrosion defect influences such as length, width and depth, cumulativesum method is used to determine the function between Mises stress and defect size. Calculating software for pipeline corrosion limit thickness is developed by Visual Basic, which provides a convenient calculating tool to engineers in practical projects.