To explore the biological mechanisms of the green manure to improve fertility of tobacco cultivation red soil，the effects of purple green manure plowing and wheat stubble plowing on microorganisms，soil enzyme activity and nutrient con- tent of tobacco cultivation red soil were studied with the control of fallow land.The results showed that: bacteria，actinomy- cetes，soil enzyme activity，soil organic matter and nutrient content of green manure treated soil were higher than those of wheat stubble treated land and those of fallow land，changes in differences were significant（ p <0.05）or highly significant （ p <0.01），and fungi of wheat stuble were higher than those.Green manure plowing land，wheat stubble plowing land and fallow land to compare: soil bacteria in Yuezhou test area were increased 1.74×10 6 ，2.61×10 6 cfu?g -1 ，actinomy- cetes increased 1.35×10 4 ，0.65×10 4 cfu?g -1 .Soil urease increased 1.50，1.68 mg?g -1 ，acid phosphatase increased 2.90，3.09 mg?g -1 ，catalase increased 1.20，2.54 mL?g -1 ，polyphenol oxidase enzyme increased 1.91，7.58 mg? kg -1 ，soil organic matter increased 16.36，26.22 g? kg -1 ，soil available N increased 42.52，54.31 mg? kg -1 ，soil a- vailable P increased 6.22，7.57 mg? kg -1 ，soil bacteria in Jinning test area increased 2.52×10 6 ，3.95× 10 6 cfu? g -1 ，actinomycetes increased 1.17×10 4 ，1.62× 10 4 cfu?g -1 ，soil urease increased 1.77，2.00 mg?g -1 ，acid phos- phatase increased 1.13，1.24 mg?g -1 ，catalase increased 1.45，2.19 mL?g -1 ，polyphenol oxidase increased 4.81， 11.34 mg? kg -1 ，soil organic matter increased 10.18，19.43 g? kg -1 ，soil available N increased 41.34，54.43 mg? kg -1 ，soil available P increased 4.79，5.86 mg? kg -1 .