Abstract: In order to analyze the effect of welding process on fatigue properties of portal crane rail, the notch stress concepts was used on the evaluation of specimens' fatigue properties. The finite element models of welded portal crane rail specimens was established, and the influence of the specimens' shape, size and boundary conditions on the notch stress value were analyzed. According to the calculation results, the S-N curve and design curve were mapped. The result shows that, the notch stress value is influenced by factors of shape, size, and boundary conditions of the specimens. Notch stress is suitable for the fatigue assessment of welded portal crane rail structure; Since the calculation results can reflect the impact of objective factors and reduce the discreteness of the experimental data. Under these circumstances, if all the specimens have the same shape, the experimental data can be characterized by one S-N curve of notch stress.