A 200nm Ti film was deposited on a polished AlN ceramic substrate at 200℃ by electron beam evaporation under high vacuum conditions and annealed in a vacuum furnace.X-ray diffraction measurement and secondary ion mass spectrometry,Rutherford backscattering spectrometry,Auger electron energy spectroscopy were used to investigate the solid phase reactions between the titanium thin film and the AlN ceramic substrate during annealing from room temperature to 850℃.Experimental results showed that after annealing beyond 600℃,diffusion and reaction took place at the interface of Ti/AlN obviously and the reaction was enhanced with increasing temperature.The titanium aluminides and titanium nitrides as reaction products at the interfaces have been found.The titanium aluminides consist of Ti-Al binary and Ti-Al-N ternary compounds,in which Ti2AlN is dominant after 4h annealing at 850℃.The results have been explained in terms of extended Ti-Al-N ternary phase diagram given by Bhansali et al.