Abstract: The limit pressure of pipeline with cracks is one of the important aspects in structure integrity assessment.We used finite ele-ment method,crack tip opening angle(CTOA) as the parameter to in-vestigate the applicability of critical CTOA in pipe line limit pressuremod-cling,which containing longitudinal penetrating crack.Here the critical CTOA was used as the critical failure rule of the pipe.Factors affectingnum erical results were also studied.Then a predictive model was estab-lished based on these results and compared with other models.From theanalysis,we could conclude that critieoula CTOA could be used t0 mode.ling penetrating crack in pipelines as long as the finite element model and element size were properly chosen.When the crack was small the known formulas would heavily underestimate pipe carrying capacity.But for largecracks,they might give overestimated results,and lead to safety problem sfor pipes.