Abstract: Using phenolic resin as binding agent, samples with sintered alumina (100wt%), fused corundum (100wt%) and sintered alumina (50wt%) mixed with fused corundum (50wt%) were prepared, respectively, then the samples were sintered at 1 500℃ and 1 600℃ under flowing nitrogen, respectively. Sintered samples were characterized by XRD, SEM and EDAS. The results show that γ-AlON(Al₅O₆N) and 12H polytype(Al₆O₃N₄) form in samples sintered at 1 500℃, while γ-AlON(Al₅O₆N), 21R polytype(Al₇O₃N₅) and 16H polytype(Al₈O₃N₆) form in samples sintered at 1 600℃. The content of AlON increases remarkably in samples sintered at 1 600℃ compared with samples sintered at 1 500℃. At the same sintering temperature, AlON contents in samples prepared with sintered alumina (50wt%) mixed with fused corundum (50wt%), fused corundum (100wt%) and sintered alumina (100wt%) decrease inturn. The formation mechanism of AlON was studied and the reaction model of alumina powder and carbonis was presented.