The invention relates to a ladle furnace use nitrogen gas nitrogen alloying process. The process comprises the following steps: a) smelting nitrogen-contained stainless steel, controlling the components of the molten steel except the nitrogen to the targeted components, and controlling a nitrogen flush initial temperature at 30 to 50 DEG C above a refining treatment out-station temperature; b) during the nitrogen bottom blowing for the smelting of the nitrogen-contained stainless steel in the LF furnace, adding 1 to 20 ppm of nitrogen to each standard cube of nitrogen; c) during the nitrogen bottom blowing for the micro-alloying treatment, controlling the nitrogen flow at 6 to 120m<3>/h and the nitrogen flush pressure at 0.60 to 0.80 MPa; and d) when the nitrogen bottom blowing is finished, carrying out the argon bottom blowing for 4 to 6 minutes with the argon flow of 2 to 20 m<3>/h so as to average the stainless steel components and temperature. The process adds the nitrogen alloying function through the nitrogen bottom flowing to the ladle furnace (LF) in the prior stainless steel production process so as to replace a nitro alloy, make the nitrogen-contained stainless steel carry out continuous and stable nitrogen alloying in the ladle furnace, improve the purity of the molten steel, and consequently improve the molten steel quality and reduce the production cost.