Abstract: Diamond/Cu composites were fabricated by powder metallurgy in a hot-pressing furnace. The impacts of the titanium film, sintering temperature and volume fraction of diamond particles on the thermal conductivity of diamond/Cu composites were investigated. The results show that the titanium film can improve the interfacial soakage, decrease porosity and increase the thermal conductivity of diamond/Cu composites. When the sintering temperature was below 980 ℃, it can not make diamond/Cu composites get enough sintering driving force, resulting in low relative density and thermal conductivity. When the sintering temperature was above 980 ℃, it can cause the interfaces to break away because of the large difference of thermal expansion between diamond particles and copper, and can make the relative density and thermal conductivity of diamond/Cu composites decrease. The increasing of the diamond particle volume fraction can cause the copper to insufficiently fill the porosity between diamond particles, and decrease the relative density of diamond/Cu composites, which results in the increasing first and then decreasing of the thermal conductivity of diamond/Cu composites.