Effects of low-molecular-weight (LMW) organic acids on mobilization of Al and distribution of mobilized Al between soil solid and solution phase were studied in two acid soils from the angle of dynamics. Results show that LMW organic acids weak in chelating ability, such as lactic acid and acetic acid, promoted Al mobilization mainly with the aid of protons. They were less effective than HCl in promoting Al mobilization. While LMW organic acids strong in chelating ability, such as malic acid, oxalic acid and citric acid, promoted Al release mainly through chelation with organic anions. This effect was more effective for organic acids stronger in chelating ability with Al. In latosol high in content of iron oxides, malic acid, oxalic acid and citric acid increased the content of exchangeable Al mainly through specific adsorption of organic anions. While they decreased the content of exchangeable Al in red soil low in content of iron oxides mainly through formation of soluble Al-organic complexes. Distribution ratio of mobilized Al between soil solution and soil solid depended on competition between organic anions in soil solution and negative charge sites on soil surface for Al ions. Thus, most Al mobilized by lactic acid and acetic acid existed as exchangeable Al, while Al mobilized by oxalic acid and citric acid was mainly distributed as soluble Al-organic complexes in soil solution, which was especially significant in red soil low in content of free iron oxides, and would promote Al mitigation from soil to water body.