Investigation on the composition and characteristics of humic substances in brown forest soils under three different vegetations was made.The results showed that the heighest content of humus was found in the soil under pure forest of Betula albo-sinensis Burk,the highest content of humic acid and HA/FA ratio were in the soil under pure forest of Quetcus liaotungensis Koidz; the contents of active humic acid in the soils under all the three forest vegetations were higher,bur the highest content was in the soil under the pure forest of Betula albo-sinensis Burk.