In this paper, diamond/AlSi composite coatings were prepared on Ti-6Al-4V titanium alloy substrates by ultrasound-assisted brazing coating technology. The effects of ultrasonic brazing coating process parameters on the micro-morphology of diamond/AlSi brazing coatings are investigated. The interfacial reaction mechanism of AlSi braze on the substrate with diamond under ultrasonic action was explored. The results show that: TiAl3 compounds and a large number of Ti(Al1-xSix)3 compounds are mainly formed in the contact interface between titanium alloy substrate and AlSi brazing material; Ti(Al1-xSix)3 growth is mainly affected by the joint influence of the interfacial reaction and the diffusion rate of the atoms arriving at the reaction site; ultrasonication using the cavitation effect can improve the effect of the AlSi brazing material"s wetting and spreading in the substrate to realize the effect of the inactivated AlSi brazing material on diamond. Ultrasound can improve the wetting and spreading effect of AlSi brazing material in the substrate by utilizing cavitation effect, and realize the wetting of diamond particles by non-active AlSi brazing material. The mechanism is that the interface between the AlSi brazing material and the substrate generates the intermetallic compound Ti(Al1-xSix)3. Through the cavitation and acoustic flow effects of ultrasound, the Ti(Al1-xSix)3 compound breaks up and disperses throughout the brazing coating, resulting in the reaction of Ti, an element in the titanium alloy matrix, with the diamond to form TiC.