Diamond reinforced copper(Cu/diamond)composites were prepared by a pressure infiltration technique. The composites show a super high conductivity of 713 W·m-1·K-1 in combination with an extremely low coefficient of thermal expansion(CTE)of 7.72×10-6 K-1(25-100℃), which are achieved by modifying the copper matrix with adding 0.3 wt% of boron to get a good thermal contact between the matrix and the diamond particles. By adopting a series of postmachining techniques the composites were made into near-net-shape parts, and an eleclroless silver coating was also successfully plated on the composites. Finally, their potential applications in the thermal management of light emitting diodes(LED)were illustrated via prototype examples.