The tungsten coating layers on diamond are obtained by a micro vacuum evaporation diffusion method, and the diamond copper composites are prepared by vacuum pressureless infiltration. The plating layer structure is analyzed with XRD, and the surface morphology of plating layer and the diamond/copper interface morphology in the composite materials are observed by scanning electron microscopy. The results indicate that the surface of diamond coated tungsten layer improves the wettability of the matrix. The thermal conductivity fist increases and then decreases with the increasing coating thickness. The full uniform plating layer on the diamond/copper interface has a high heat conductance.