The physicochemical properties，denitrification differences and related microbial composition in soil under four rotation and fallow patterns including B （Chinese milk vetch - early rice- maize || batatas） ，C （ rapeseed - sugarcane || spring soybeans），D （Chinese milk vetch - spring soybeans - autumn soybeans ） and E （annual fallow） were compared and analyzed using the traditional cropping pattern A （Chinese milk vetch-early rice-late rice） as the control to study the effects of different rotation and fallow patterns on the nitrogen loss，the denitrification potential and related microbial community structure in soil of paddy fields.The acetylene inhibition method was used to determine the denitrification rate.The high-throughput sequencing was used to analyze the diversity and composition of denitrifying microbial communities.The results showed that the denitrification potential in soil under four rotation and fallow patterns was significantly lower than that under the control，which effectively reduced the gaseous loss of nitrogen in soil.There were significant differences in the community structure of functional genes nirK and nirS under different rotation and fallow patterns，among which the community structure of gene nirK was less affected by the rotation and fallow patterns than that of gene nirS.Compared with the control，the E pattern was more conducive to the accumulation of α-diversity of gene nirS.In terms of the relative species abundance of nirS and nirK gene communities，the abundance of dominant species under four rotation and fallow patterns was higher than that under the control，and the abundance of fungal genera in the pattern B and pattern E was relatively higher.The key genera affecting denitrification potential were Bradythizobium （r² = 0.85，P<0.05） and unclassified_p，Proteobacteria （r² = 0.88，P <0.05）.The results of correlation and redundancy analyses showed that pH，the available phosphorus （AP），available potassium （AK） and nitrate-nitrogen （NO₃^--N） in soil was significantly correlated with the denitrification potential in soil，while the important factor affecting the community structure of gene nirK and nirS was the content of water in soil （SWC）.It is indicated that the rotation and fallow patterns of appropriate water-drought and dry-drought crop in paddy fields can change the flooding environment in soil，affect the community structure of gene with denitrification function，help inhibit the gaseous loss of nitrogen in soil，and promote the improvement of the fertility and structure in soil，among which the pattern B and pattern E is the best.