A field long-term conservation tillage experiment was conducted to study the effects of four cultivation modes (turnover tillage, no-tillage, turnover tillage + straw-return, and no-tillage + straw-return) on the soil enzyme activities and microbial biomass in different soil layers. The results showed as follows: 1) In the soil layers of 0 – 10 cm and 10 – 20 cm, the enzyme activities were higher in the treatments of no-tillage than in the treatments of turnover tillage, being the highest under no-tillage + straw-return and the lowest under conventional tillage. 2) In the soil profile of 0 – 10 cm and 10 – 20 cm, the soil microbial carbon and nitrogen were higher in the treatments of no-tillage than in the treatments of turnover tillage, and which in the treatments of stubble-remaining were higher compared with no stubble-remaining. 3) Soil enzyme activities, soil microbial carbon and nitrogen all reduced with the increasing of soil depth and reached significant levels of differences in the all three soil profiles.