It is well known that vanadium alloy will face to strong neutron irradiation and hydrogen environments as a structural material in a fusion reactor. Some researches have reported that vanadium alloy took strongly hardening after an exposure to hydrogen environment and irradiation by neutron at a temperature lower than 400 ℃[1 -3]. The ductility of the alloy was lost largely, even entirely brittle fracture It is well known that vanadium alloy will face to strong neutron irradiation and hydrogen environments as a structural material in a fusion reactor. Some researches have reported that vanadium alloy has been hardened after an exposure to hydrogen environment and irradiation by neutron at a temperature lower than 400 ° C [1 -3]. The ductility of the alloy was lost largely, even entirely brittle fracture