Diamond/copper composites have high thermal conductivity, and they can be used to solve the problems of packaging and heat dissipation of future high heat flux electronic component. They have attracting more and more attention. In this paper, the manufacturing methods of diamond/copper composites, the influencing factors of thermal conductivity and interface problems are reviewed. Four main preparation processes, including hot pressing sintering, high temperature and high pressure sintering, spark plasma sintering and infiltration, are summarized. Diamond particle parameters and sintering process parameters have important effects on the thermal conductivity of diamond/copper composites materials. There are two methods to solve the interface problems of diamond indicate premetallization and copper matrix alloying. The above topics and the applications are the emphasis and development trend of diamond/copper composites in the future.