Abstract: The method of vacuum evaporation-diffusion plating was used to plate titanium on diamond, the effects of plating temperature and holding time on diamond surface morphology, coating thickness and coating phase were studied, and the anti-oxidation performance of Ti-coated diamond was analyzed as well as its bonding state in iron matrix. The results showed that TiC appeared at low temperature(680℃). The plating temperature increasing or the holding time prolonging, the coating became denser and thicker, titanium deposition occurred at 720℃, cracks occurred due to stress and led to the destruction of the coating at 820℃. The coating isolated the direct contact between diamond and oxygen, and the erosion of diamond by oxygen was greatly delayed. After titanium plating, the diamond achieved solidly metallurgical bonding in the matrix.