With the magnesia-rich spinel as the main raw material, adding four alumina sources of activated alumina, ρ-Al2O3, Al(OH)3, industrial alumina, respectively, the magnesium aluminate spinel was prepared after sintering at temperatures of 1 550-1 700℃. The effect of alumina source on the sintering behavior of the magnesia-rich spinel was studied, and the phase composition and microstructure of the magnesium aluminate spinel were analyzed. The results show that the effects of different alumina sources on the sintering behavior of magnesia-rich spinel were different. The addition of activated alumina was in favor of the sintering densification, while with the addition of ρ-Al2O3, Al(OH)3 and industrial alumina, the influence was unfavorable. When sintering at the temperature under 1 650℃, the synthetic magnesium aluminate spinel was mainly fabricated by the reaction of free magnesia and alumina, while a little alumina was solid solved in the spinel lattice at the temperature over 1 650℃. After sintering the magnesia-rich spinel with activated alumina at 1 700℃ for 3 h, the obtained magnesium aluminate spinel had a good grain growth and a dense structure.