SKD 11 steel is high quality steel that is made to be applied as a cutting tool, forming tool, and as a mold. SKD 11 steel is tool steel that is widely used in industry because of its high chromium content so it has good stability when hardening and has high wear resistance characteristics. SKD 11 steel has an initial hardness of 17HRC, this hardness needs to be increased to increase strength and toughness so that it can be used as tool steel. Therefore hardening treatment is carried out by diffusion coating and diffusion coating with vacuum process. This study aims to determine the effect of diffusion coating and diffusion coating-vacuum treatment to obtain mechanical properties and microstructure of SKD11 material. This study uses vanadium and borax as a material to increase the hardness of the material. The process of heat treatment done in this research include preheat, Toyota diffusion, washing, vacuum, and tempering. The test method is a process of hardness testing with Rockwell C, a hardness test process with Vickers, a wear resistance test process and a microstructural testing process on SKD 11. Results of analysis of the treatment diffusion coating and diffusion coating with additional vacuum, layer thickness after the treatment diffusion coating and vacuum process of 9 micro meters on the material layer of SKD 11. The coating is thought to be vanadium carbide, not only on the surface but also the coating into the substrate of the material that makes the mechanical properties increased. The diffusion coating process increases the hardness value from 200 HV to 956 HV on the surface and 628 HV on the substrat. The result of wear resistance testing has also shown a result of 3.442 x mm²/kg on treatment diffusion coatings and 5.65 x mm²/kg on diffusion coatings with extra vacuum.