The invention discloses a composite processing method for realizing metallization of the surfaces of diamonds. The method comprises the following steps: performing chemical plating processing on diamond particles to enable the surfaces of the diamond particles to be uniformly coated with chemical plating layers; performing metallized processing on the surfaces of the diamond particles, packing a wave-absorbing material and the diamond particles subjected to chemical plating into a ball mill jar for realizing uniform material mixing, filling a corundum crucible with the mixture, sealing the surface of the corundum crucible and placing the corundum crucible in a vacuum micro-wave heating oven, and slowly rotating the oven for heating and insulating, wherein the heating temperature is 750-900 DEG C, the heating and insulating process takes 10-30 minutes, and the vacuity is 1.3*10<-3>Pa; separating the diamond particles from the wave-absorbing material. According to the invention, the chemical plating technology and the vacuum microwave quick heating technology are combined, so that the deposition temperature of the chemical plating becomes low, and obtained plating can be more uniform and compact; heat energy can be more effectively utilized through vacuum micro-wave heating; moreover, metallurgy diffusion reaction rate is promoted, the processing time is shortened, and graphitization of the diamonds can be well prevented in a vacuum processing environment.