Soil drought is akey bottleneck restricting agricultural production inChina.Applying bio -organicfertilizers(BF) can effectively increase soil organic mattercontent，improve soilphysicochemicalproperties，and promote cropgrowth.However，its effects onwater retention and bacterial community of dryland red soil is rarelyreported.Therefore，this study explored the impact of BF application on soil water retention by measuring the dynamic changes of soil water content under different applicationamounts，moreover，bacterial community was analyzed by high-throughputsequencingtechnology. The results showed that the effect of applying BF on soil water retention was different due to the difference of applicationamount and simulated drought period.When the application amount was 1% and the simulated drought period was31days， soil water content was1.8 times than that of theCK.The application of BF significantly increased the content of soil organic matterand availablenitrogen，available phosphorus，and available potassium，and it was increased with the increase of applicationamount.The application of BF significantly affected the composition and diversity of soil bacterialcommunity. Compared withCK，the relative abundance ofProteobacteria，Bacteroidetes，Acidobacteria，and Actinobacteria in soil wasincreased，and Firmicutes wasdecreased，moreover，the bacterial diversity was increased significantly under BFapplication(P<0.05).The application of BF significantly increased the relative abundance of Lysobacter，Ramlibacter， and Sphingomonasin the soil in aridenvironments，however，the relative abundance of Bacillus wasdecreased，which wasrelated to the changes in bacterial habitats caused byfertilization.Therefore，our study suggested that proper application of BF could be an effective measure to cope with seasonal soil drought and regulate bacterial community.