Abstract: Field experiments were conducted to study the effects of returning green manure on the relationship between enzyme activities and fertility in tobacco-planting soils. The results show that the returning green manure could obviously increase the soil enzyme activities and soil nutrients. In comparison with the control, the treatments which the returning green manure amounts are more than 15000 kg/ha, especially between 22500 and 30000 kg/ha, the effects on soil enzyme activities and nutrients are more obviously. In comparison with the control, the activities of soil urease, acid phosphatase（ACP）, invertase and catalase are increased by 13.10%-23.81%, 12.92%-29.38%, 75.35%-234.51% and 29.17%-37.08% respectively. Soil organic matter, total N, akalytic N, available P, available K, pH, and porosity are increased by 13.01%-70.41%, 6.42%-27.52%, 1.14%-10.99%, 15.97%-34.99%, 10.28%-38.30%, 2.74%-7.05%, 0.19%-2.50% respectively. Soil bulk density is decreased by 147%-515%. The results of correlation analysis reveal that there are significant positive correlations between soil edaphic physicochemical factors and activities of soil urease, acid phosphatase, invertase and catalase. The linear function of the first pair of canonical variables reveals that soil enzyme activities and soil fertility factors are indicators of soil comprehensive fertility, and the linear function of the second pair of canonical variables reveals that the effects of green manure application on the changes of some physiological and biochemical processes of tobaccoplanting soils. The results of principal components analysis show that the first principal component is the composite indicator of reflecting soil fertility level, all the factors have actively influence on soil fertility. Four soil enzymes are in the first principal component, and more closely correlate with soil fertility, so soil fertility could be objectively evaluated by soil enzyme activities and edaphic physicochemical factors, and using soil enzyme activities and edaphic physicochemical factors to characterize the soil fertility is feasible. The above results reveal burying green manure could promote the activity of soil organism, it is in favor of the turnover of organic matter in the soil and provision of nutrition to meet the needs of tobaccos normal growth.