Abstract: A finite element model of a heat exchange tube with a semi-elliptical crack in the cross section of the inner surface, which simulates the crack tip's stress singularity, was established by ANSYS software. After discretizing the crack front, crack fronts in different crack propagation orientations were presented. Under different thermal-mechanical coupling loads, the stress intensity factors K_I of the finite element model were calculated and compared at different crack parameters. The distribution rule of K_I and its influence factors were discussed in detail.