Abstract: Diamond reinforced copper matrix composites were prepared by hot pressing sintering method. The microstructure and composition of the samples were analyzed by SEM, EDS and XRD, and the properties of the samples were measured by digital microhardness tester and conductivity detector. The effects of titanium content on the microstructure, density, electrical conductivity and hardness of diamond reinforced copper matrix composites were further studied. The experimental results show that the addition of a certain amount of Ti can significantly improve the conductivity and hardness of diamond reinforced copper matrix composites during the hot pressing sintering process. After the addition of 0.5wt% and 1wt% Ti into the Cu-5D sample with 5wt% diamond at 50 MPa and 950 ℃, the conductivity increases from 44%IACS to 61%IACS and 66%IACS, respectively, and the hardness increases from 78.6 HV to 85.4 HV and 111.7 HV. It is concluded that the TiC interfacial layer is formed by the reaction of Ti with diamond, which improves the density of the composites and the interfacial bonding between diamond and matrix, thus improving the conductivity and hardness of the composites.