Abstract: A field trail with a random block design was carried out in cabbage field with three replicates.There were total four treatments: JG1 （low usage of straw returning， 7 500 kg·hm-2）， JG2（medium usage of straw returning， 11 250 kg·hm-2）， JG3（high usage of straw returning， 22 500 kg·hm-2） and nonstraw returning（the control）. We compared the difference of soil carbon and microbial community functional diversity among different treatments. The result showed that compared with the control， straw returning could significantly enhance the contents of soil microbial biomass carbon （MBC） and watersoluble organic carbon （WSOC）， with 127.0%-147.7% and 54.1%-69.4%， respectively. Soil microbial activity （AWCD） values， the microbial diversity indexes （H） and evenness index（E）in the treatments of medium and high usage of straw returning were much higher than that of the control （P<0.05）， the cabbage yield were increased by 16.6% and 11.1%，respectively. In a word， corn straw returning is an effective soil management practice for improvement of soil quality.

Key words: corn straw, soil organic carbon, water soluble organic carbon （WSOC）, microbial biomass carbon （MBC）, microbial functional diversity