Abstract: The soil microorganism and enzyme activity in different interplanting modes and different aged stands of poplar planted forest in Dongting Lake area were studied. The results showed that: (1) interplanting could promote the growth of forest trees, compared to forest without interplanting, diameter at breast height (DBH) showed significant difference, tree height showed extremely significant difference; (2) soil microbial quantity of the same age forest of different interplanting patterns was in the order of interplanting cabbage> interplanting pumpkin> no interplanting, interplanting could increase soil microbial quantity; among different age forests, soil microbial quantity of 2 and 8 years forest was relatively large, that of 4 years was relatively small; reeds had the largest number of microorganisms, which was significantly different from other forest lands; (3) the change ranges of soil sucrose, urease and catalase activities in different forest types were 3.39- 6.06, 0.81-1.83, 2.18-2.26 mg/g; the difference between soil sucrose and urease activity was not significant, the catalase activity in 4 years forest and reeds were the least, which reached significant difference with interplanting cabbage; soil enzyme activity in interplanting cabbage and 8 years forest were the highest; (4) there were significant correlations between soil fungi and bacteria and actinomycetes in poplar forest, soil urease were positively correlated with sucrose, and negatively correlated with catalase, urease and sucrose were positively correlated with fungi, bacteria and actinomycetes, catalase was negatively correlated with fungi,