Abstract: MAX ceramic bonded diamond composites were fabricated by microwave sintering from MAX phases and diamond raw powders.The effect of MAX phase and diamond content on phase and micro-structure of composites were studied.The result showed that different coating on the diamond could be obtained after microwave sintering.MAX phases'type and diamond had a different effect on the matrix composition and surface coating of diamond.Ti₂SnC might be obviously decomposed to Sn and TiC in the Ti₂SnC-diamond composites.When diamond content was lower,its surface was smoother.Additionally,small amount of circle organization were formed on the diamond.When diamond content was higher,many fine TiC grains were formed on the diamond.Ti₃AlC₂ may be also obviously decomposed to Al and TiC in the Ti₃AlC₂-diamond composites after sintering.Diamond was eroded obviously.Al₄C₃ and Al₂O₃ organization were formed on the surface of diamond.In Ti₃SiC₂-diamond system,the main phase of the matrix was Ti₃SiC₂.When diamond mass fraction was 10%,small amounts of Si,TiSi₂ and SiC were obtained.When diamond mass fraction was 20%,tiny TiC was obtained.SiC and TiSi₂ binary organization were formed on the diamond.