Silicon was used as the only combustible agent, and single-phase Y-α-SiAlON powders were fabricated from a proper starting composition, but the grain morphology of the products was represented by equiaxed microcrystals. For the same starting materials, as a modified method of combustion synthesis was applied, single-phase Y-α-SiAlON powders were also obtained and the grain morphology of the products changed to rod-like microcrystals. It is of great importance to control the reaction temperature to tailor the grain morphology of Y-α-SiAlON microcrystals.