Abstract: Thermo-Calc software was used to calculate the pseudo binary equilibrium phase diagram of ultra-high nitrogen steel containing V. By means of metallographic microscope and scanning electron microscope, the aging precipitation behavior of ultra-high nitrogen steel containing V was studied, and the mechanical properties were tested. The results show that the addition of V elements causes MX-type nitrides to precipitate between 1131-1203 ℃. 1230 ℃/1h solution treatment and aging treatment at different temperatures make VN disappear, and as the aging temperature increases, the VN size tends to grow. The Cr₂N phase gradually precipitates below 1203 ℃, and the Cr₂N content increases with the increase of the aging time during the aging process at 900 ℃. The precipitation of Cr₂N reduces the mechanical properties of the test steel, especially the elongation decreases rapidly.