Abstract: The structure and load is complex at the nozzle of pressure vessel, a crack is supposed in the corner angular of the RPV inlet nozzle and it is a mixed model crack while considering the pipe load. A three-dimensional finite element model with the supposed crack is established and the SIF（Stress Intensity Factor） distribution and variation of the crack tip with pipe load and internal pressure is analyzed. The results show that the SIF is approximately in symmetrical distribution in the crack tip and the SIF K_I, K_II, K_III are small with pipe load, and internal pressure do not affect the SIF K_II and K_III of the crack tip.