Out of 19 different genotypes of soybeans(Glycine max),Variety Zhechun No.2(Al-resistant)and Variety Zhechun No.3(Al-sensitive)were screened and selected as subjects in this study,which was designed to have 5 different aluminum(Al³⁺)treatments 0,0.2,0.4,0.6,and 0.8 g kg^-1,(i.e.0.293,0.493,0.693,0.893,and 1.093 g kg^-1,respectively,in soil total Al³⁺)and 3 parallel treatments(non-rhizospheric soils,rhizospheric soils and bulk soils with exogenous soybean exudation).Thirty days after the treatment,respiration rate,cellulose hydrolysis efficiency,ammonification rate,nitri-fication rate of the soils,and activities of acid phosphatase,catalase,and sucrase were measured.Results indicate that in treatments low in soil Al(0.2 and 0.4 g kg^-1),irritated secretion from the soybean roots increased the population of soil microbes, strengthened their capability of material transformation and stimulated the activity of soil enzymes,whereas in treatments high in soil Al(0.8 g kg^-1),root exudation was restrained comparatively,result ing in inhibition of the activity of microorganisms and soil enzymes.The results also demonstrated that exogenous root exudation could also influence the microbial ecosystem,triggering changes in activity of the soil enzymes and in major biochemical functions of the soil,thus mitigating aluminum poison to soybean,which is convincing evidence that root exudation obviously affects the microbial ecosystem.