Abstract: In order to study the N-content and porosity of the weld metal of high nitrogen steel 1Cr22Mn16N, the steel was welded by CO₂ laser welding, and the influence of the shielding gas composition and heat input on the N-content and porosity of the weld metal was investigated.The experimental results indicate that the N-content of the weld metal increases slightly as the nitrogen in the shielding gas containing Ar and N₂ is increased under the same heat input. The N-content of the weld metal decreases with the increase of the heat input when pure Ar is used as the shielding gas, whereas that of the weld metal is improved with the increase of the heat input when enough nitrogen is added to the shielding gas.The higher the heat input, the less the porosity in the weld metal, and the more N₂ in the shielding gas, the less the porosity forms.