Abstract: To reveal characteristics of short term mechanized returning straw to the field by wide/narrow row on soil microbial diversity，changes of microbial community diversity and its relationship with soil physical and chemical factors in fluvo-aquic soils in wheat planting area and corn straw furrow at 0~20，20~40 and 40~60 cm depths under maize/wheat alternate planting mode were analyzed based on high-throughput sequencing method.Results showed that the Shannon index of soil microbial diversity decreased with increase of soil depth for both two types of soil.At the same depth，microbial diversity of corn stalk returning ditch samples was generally higher than that of wheat planting soil.The community structures of soil samples from different areas and different depths were quite different.At the phylum level，the dominant phyla in two soil samples were Proteobacteria，Bacteroidetes，Gemmatimonadetes，Acidobacteria and Acitinobacteria.The relative abundances of Proteobacteria and Bacteroides in wheat planting area were slightly higher than those of corn stalk returning ditch samples，while abundances of Gemmatimonadetes，Acidobacteria，Actinomycetes，Chloroflexi and Firmicutes were lower than those of corn stalk returning ditch samples.At the genus level，Lysobacter，Altererythrobacter and Sphingomonas were the dominant genera.Total nitrogen，alkali hydrolyzed nitrogen，available phosphorus，available potassium and organic matter were positively correlated with Chloroflexi，Acidobacteria，Acitinobacteria，Gemmatimonadetes，but negatively correlated with Proteobacteria and Bacteroidetes.The copy numbers of carbohydrate metabolism functional genes in topsoil of corn stalk returning ditch were significantly higher than those of wheat planting top soil.Straw returning increased microbial diversity of soil，which laid a solid foundation to further optimize straw returning method and to improve soil ecosystem.