Abstract: In order to find out the relationship between humic acid content and the change of mercury morphology in brown soil with time,the effect of the dosage of humic acid on mercury species in polluted brown soil were explored,through the incubation experiment indoor.The results showed that adding humic acid changed the distribution ratio of various mercury in brown soil and it could decrease the contents of Ws-Hg,Ex-Hg,Aci-Hg and Res-Hg,but increased the contents of Ob-Hg and Alk-Hg remarkably,compared with no humic acid treatment various forms of mercury reached significant level (p