The microstructure and properties of Al-Ti-C master alloy prepared by titanium hydride and graphite were studied by X ray diffraction (XRD)、scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The results show that the mechanism of Al-Ti-C alloy prepared by the reaction of titanium hydride-graphite and aluminum liquid is that (1) Titanium hydride and graphite are respectively used as titanium and carbon sources, and titanium and hydrogen are obtained by thermal decomposition of titanium hydride.(2)Titanium react with aluminum and graphite to form titanium-aluminum、titanium-carbon or carbon-aluminum compounds.(3) Titanium aluminum, carbon aluminum and titanium carbon compounds have refined Al-Ti-C alloy.The phase composition of the alloy includes α(Al), Ti-Al,C-Al, Ti-C compounds and other phases. The microscopic structure is equiaxed or dendrite structure, and the average grain size is 20～40μm.There are needle like or rod like primary crystals in the alloy matrix. There are petal like primary crystals containing titanium, carbon, iron and silicon on the grain boundaries. The titanium and carbon elements distribute evenly along the grain boundaries and the grains. There is obvious titanium and carbon enrichment and segregation near the primary phase.Cryolite is conducive to the wetting and reaction of carbon and aluminum, the second phase generated more fully and uniform diffusion in the grain.