Effects of rare earth element La on the microstructure of Cu matrix diamond tools were researched under the conditions of various materials componentsand the process parameters in order to improve materials properties. SEM, XPS and X-ray were used to investigate the fracture section, microstructure and the element valence in materials. The results shown that the combination of rare earth element La and transition element Ti is advantageous to the bonding state between diamond particles and matrix, so it can improve the materials properties. Suitable sintering temperature is 790℃.