Cu/diamond composite was produced by vacuum second hot-pressing and repressing and re-sintering technology.The effects of different sintering processes,powder mixing processes and the diamond particle size,volume fraction on the relative density and micromorphology of composites were studied.The results show that the relative density of composites prepared by vacuum second hot-pressing is higher than that by repressing and re-sintering,and the second hot-pressing obviously enhances the relative density of composites.The maximum relative density of 98.45% of the composite with diamond volume fraction of 40% is obtained,with diamond particle size of 90 μm.