Abstract: In order to investigate the ecological functions of green manure in improving soil, field experiment in 3 consecutive years were conducted to study the effect of different green manure application on the microbial biomass and enzyme activities of tobacco-planting soil. The results showed that green manure turnover could increase soil microbial biomass and soil enzyme activities. Compared with control, the total activities of soil microorganism were increased by 196.44%, and the amounts of bacterium, fungus, actinomyces increased by 36.29%, 82.88%, 9.16%, respectively. The activities of invertase, catalase, phosphatase and urease were increased by 35.82%, 10.57%, 17.13%, and 15.89%, respectively. The influence of consecutive green manure turnover on soil microbial biomass was bigger than soil enzyme activities. The influence of gramineous green manure application on the microbial biomass and enzyme activities of tobacco-planting soil was the biggest, with the next being leguminous green manure, and cruciferae green manure being the smallest. Thus, application of green manures could improve soil environment of tobacco field and be favorable to the sustainable development of tobacco production.