The clear liquid fermentation has many advantages.This paper studies the influential patterns of acid ion on Acetone-butanol clear liquid fermentation with corn starch as carbon source.The results showed that:SO32-has the strongest inhibitory ability,and this ability enhances with increasing ion concentration.The fermentation is normal when the corresponding concentration of sodium salt,ammonium salt to SO42-,Cl-,CO32-,Ac-,PO43-is in the range of 0.2～1.0 g/L.The highest yield achieved was 22.091g/L.The appropriate concentration can play a certain enzymatic effect.When the concentration corresponding salt of SO42-,Cl-increase to 2.0 g/L,the solvent production declined slightly,and there was little effect of the other three acid ion.Mixture of several kinds of salt in the fermentation at varies concentrations proved that the fermentation was normal with no sulfite,and it was abnormal with sulfite,where the solvent production was as as 1.806g/L.Similarly,strong inhibitory action of SO32-was proved on the fermentation.