Abstract: Reactor pressure vessel (RPV) is the critical un-changeable component of the reactor during its service lifetime, which prevents the radioactive leak of the nuclear power plant core. The irradiation test (about 10×10¹⁹ cm^-2, E≥1 MeV) of the pressure vessel material of China A508-3 steel in research reactor was carried out, and the mechanics performance tests were carried out after the neutron irradiation, including tensile property and impact property. The results show that the yield strength increases by 83, 108 and 52 MPa, and the tensile strength increases by 58, 61 and 49 MPa at -100, 20 and 288 ℃, respectively. The ductile-brittle transition temperature T_41J increases by 68 ℃, and the upper shelf energy decreases by 61 J. Meanwhile, by comparing the property of un-irradiated and irradiated material, after irradiated to the level of 60 a service life, A508-3 steel still meets the reactor operation requirement.