The equilibrium oscillating method was adopted to study the effect of Al2(SO4)3 on the adsorption of fluoride in soda alkali saline soil by adding different ratios of Al and F. The results showed that adsorption equilibrium time was shortened by Al2(SO4)3. The adsorbed F quantity was increased but the desorption rate decreased with adding Al amount and adsorbing time increasing. The adsorption quantity was 640.45 mg/kg in the 1︰1 Al to F treatment, 6.5 times higher than that in the no Al added treatment. But its desorption rate was the lowest which was 24.7%, 0.3 times of the control. These were related to the formation of Al-F complex and hydroxy aluminum-montmorillonite complex which produced by hydroxy-aluminum and montmorillonite in the soil after pH deceased in soil solution by Al3+ hydrolysis. Thus, Al can improve the capacity of soda alkali saline soil adsorbing F and decrease desorption rate. These makes F migrate less and decreases its bioavailability in the soil.