Abstract: 316L stainless steel is a candidate structural material for pressurized water reactors and needs to withstand the effects of radiation during service. In order to explore the effect of radiation on the microstructure and properties of 316L welds and the mechanism of action. The changes of surface morphology, microstructure, microhardness and electrochemical corrosion performance of 316L steel welds irradiated by helium ions were systematically studied. The results show that after 150 keV helium ion irradiation, a large number of small holes are formed on the surface of the sample, which leads to a decrease in the corrosion resistance of the sample. The corrosion current density of base metal and weld metal increased by 5.42 × 10⁻⁵ and 5.91 × 10⁻⁵ A/cm⁻², respectively. Irradiation leads to defects such as helium bubbles and dislocations inside the sample. These defects cause the sample to produce radiation swelling and radiation hardening. The swelling rate of the base metal and the weld are 0.103% and 0.181%, respectively, and the microhardness has been increased by 2.33 and 2.55 GPa, respectively. The EBSD test method confirms that the weld metal has a larger grain size, which makes its radiation resistance slightly worse than that of 316L steel.