Abstract: Corrosion defects can affect the ultimate bearing capacity of pipelines, and X80 pipes are the main material used in long-distance pipeline projects such as the West-East Gas Pipeline. Therefore, numerical simulation research on predicting the ultimate load of X80 oil and gas pipelines containing corrosion defects has great engineering significance and value. Based on the characteristic dimensions and corrosion defect data of X80 pipeline, a full-scale numerical finite element model of X80 pipeline is established using commercial finite element software. Actual boundary conditions and internal pressure load of the pipeline are applied in the numerical model. The ultimate load of X80 pipeline without and with defects was analyzed, and the results showed that the maximum Mises stress was located at the transition between the bottom of the defect and the smooth circular arc surface. The depth and length of the defect have a mutual influence on the ultimate load of the pipeline. Finally, a prediction method for the ultimate load of X80 oil and gas pipelines with corrosion defects was proposed, and compared and demonstrated with actual test data of X80 pipelines. The results showed that the prediction method had high calculation accuracy and good applicability.