Abstract: The strategy of in-vessel core catcher (IVCC) can be applied to achieve in-vessel retention on the condition of serious accident in pressured water reactor (PWR). The IVCC is a part of reactor pressure vessel (RPV) and it can’t be replaced in life span of nuclear power plant. In addition, it endured neutron irradiation in long-term. The typical PWR RPV model and IVCC model were studied. The results show that IVCC don’t change fast neutron flux in pressure vessel, and it don’t influence the RPV irradiation result. Furthermore, the thermal neutron flux of pressure vessel obviously reduces, and the total irradiation level of pressure vessel reduces. The IVCC can’t make against irradiation performance of the RPV, and it is useful for avoiding aging of RPV adversely.