Abstract: The 20Cr13 martensitic stainless steel was quenched at 990 ℃ and tempered at different temperatures ranging from 200 ℃ to 600 ℃. The effects of different tempering temperatures on the microstructure and mechanical properties of 20Cr13 stainless steel were investigated by using hardness tests, tensile and impact tests, combined with scanning electron microscope (SEM) and X-ray diffractometer (XRD) analyses. The results indicate that, with the increase of tempering temperature, the martensite structure continues to decompose and transforms to tempered troostite and sorbite. Carbides gradually precipitate, aggregate and grow between martensite laths and the original austenite grain boundaries, and begin to be evenly dispersed and spheroidized. The hardness of the material decreases from 515 HV to 314 HV, and the strength plastic product decreases from 14.1 GPa·% to 11.3 GPa·%. However, the impact toughness experiences a change of first decreasing and then increasing, decreasing from 24 J/cm² to 12 J/cm² and then increasing to 50 J/cm². Especially at 400 ℃ tempering, temper embrittlement is produced, and the impact fracture presents a large number of cleavage planes and river patterns, accompanied by cracks. Combined with the requirements of cutting tools for strength and toughness, 20Cr13 martensitic stainless steel shows the best comprehensive mechanical properties under the conditions of water quenching at 990 ℃, and tempering at 200 ℃ then air cooling.