Crack was one of the most dangerous pressure piping flaws. Beyond that, it was the main cause of pressure pipeline accidents. Based on related concepts of fracture mechanics, the 3-D models of pressure pipeline subjected to internal pressure and its surface oblique cracks under different Angles were established according to the ANSYS finite element software. In addition to that, the stress intensity factor of crack tip was calculated and analyzed by the finite element and the change rules between the stress intensity factor and crack Angles were concluded. According to that, the crack tip stress field strength was analyzed quantitatively. At the same time, it also provided some data supports for the study of inclined crack on the surface of pressure pipeline.