The work aims to improve the corrosion resistance and wear resistance of Cr18Mn21Mo2.5 steel. 9 kinds of orthogonal design solid solution nitriding steel were prepared by medium frequency induction furnace. The test steel with the highest nitriding efficiency (Cr18Mn21Mo2.5 steel) was obtained by the extreme difference analysis of orthogonal test, and the solid solution nitriding treatment was carried out with high purity nitrogen at atmospheric pressure. At the same time, the corrosion resistance and wear resistance of the nitriding layer were tested and analyzed. The microstructure and phase composition of Cr18Mn21Mo2.5 steel and its nitriding layer were studied by optical microscope and XRD. The hardness distribution of Cr18Mn21Mo2.5 steel after solid solution nitriding was characterized by microhardness tester. The corrosion resistance and wear resistance of Cr18Mn21Mo2.5 steel after solid solution nitriding were studied by electrochemical workstation and high speed current carrying tester. Single austenite layer with thickness as high as 1.4 mm (1200 ℃, 24 h) could be prepared under the optimized preparation process because the prepared Cr18Mn21Mo2.5 had excellent strength and flexibility. After the nitriding, the corrosion potential was improved and the corrosion current was reduced. Compared with the unnitriding sample, the impedance arc radius of the nitrided (1200 ℃, 24 h) sample increased from 2500 Ω to 8000 Ω, the friction coefficient decreased from 0.33 to 0.28, and the wear weight loss decreased from 15.5 mg to 8.7 mg. After nitriding, the corrosion resistance and wear resistance of ACr18Mn21Mo2.5 steel were improved obviously. After solid solution nitriding, N enters into Austenite lattice gap and solid solution N promotes the reconstruction of passivation film. At the same time, the solid solution strengthening of N improves the surface hardness of material. The increase of N content and the thickness of nitriding layer are beneficial to improving the corrosion resistance and wear resistance.