TiO2/Al2O3 film can be coated on the surface of diamond by sol coating process, followed by the determination and analysis of the surface morphology and properties of diamond before and after the Sol coating process by means of scanning electron microscope, energy spectrum analysis, infrared spectrum, X-ray diffraction, contact angle measuring instrument, Zeta potential and high temperature phase detector. Experimental results show that TiO2/Al2O3 film coating on the surface of diamond can be realized by the sol coating process, with the chemical bond of the interface connected by C—O—Ti and Ti—O—Al. With anatase, rutile, γ-Al2O3 and Al2TiO5 being the main substance of crystal structures of TiO2/Al2O3 film, it helps to improve the hydrophilicity and the wettability of the ceramicsof the diamond surface.