Abstract: A method of surface metallization of diamond, temper powder diffusion heat treatment, was developed. A powder mixture of elemental Cu (or Co), carbide-forming element Ti (or Cr) and diamond was heat-treatmented under vacuum. Carbide and metal film were formed on the diamond surface through solid diffusion reaction or diffusion reaction in presence of liquid phase. The bonding strenth of matrix material and the diamond was improved by using coated diamond. The bending strenth of matrix material with coated diamond was 9%-12% higher than that of matrix material with uncoated diamond.