Influence of soil moisture regime (non-flooding,flooding-drying,and flooding) on microbial community diversity and activity was investigated by determining Biolog sole carbon source utilization pattern,phospholipid fatty acid (PLFA) profiles and enzyme activity indices.Increased dehydrogenase and invertase activities were observed in Treatment Flooding as compared to what in the other two treatments,which apparently led to enhanced soil basal respiration.The average well colour development (AWCD) of the carbon sources on Biolog plates was significantly lower in Treatment Non-flooding than in the other two treatments.The fungal indicator (18:2w6,9c) and the proportion of fungal biomarker (18:2w6,9c) to bacterial biomarkers (15:0i+15:0a+16:0i+16:1w5c+17:0i+17:0a+17:0cy+17:0+18:1w7c+19:0cy) were lower under flooding conditions.The relative abundance of cyclopropyl fatty acid 19:0cy was not affected by moisture regime,however,the relative abundance of 17:0cy was the highest in Treatment Non-flooding.Cluster analyses of the sole carbon source utilization and PLFA data demonstrated that Treatment Non-flooding differed from the other two treatments in soil microbial community.Although certain similarity was found between Treatment Flooding and Treatment Flooding-drying in structure and functional diversity of soil microbial community,the findings of the study suggested that there were some drastic changes in microbial community composition and activity associated with variation of soil moisture regime.