The study focused on the effects of biochar application on the physicochemical properties of soil and the microbial community in the rhizosphere of cotton fields in Xinjiang. Cotton rhizosphere soil was collected from four treatments: Control (CK), biochar 3 t/hm2 (BC1), biochar 6 t/hm2 (BC2), and biochar 9 t/hm2 (BC3). The changes in soil properties and rhizosphere soil microbial community structure and composition were analyzed. After biochar application, soil pH and electrical conductivity (EC) decreased by 5.58 % -9.18 % and 5.38 % -18.04 %, respectively. Compared with CK, biochar application significantly increased the soil organic matter contents (SOM), total nitrogen (TN), total phosphorus (TP), alkali hydrolyzed nitrogen (AN), and available phosphorus (AP), and BC3 had a positive effect, but biochar application significantly reduced soil potassium content. Biochar application significantly reduced the relative abundance of Planctomycetota, Gemmatimonadota, Firmicutes, and Mortierellomycota. However, the relative abundances of Ascomycota, Skermanella, Bryobacter, Chaetomium, Cephalotrichum, Chrysosporium, and Pyrenochaetopsis were increased. In addition, biochar application reduced microbial diversity and bacterial richness in their rhizosphere soil, but increased fungal richness in the rhizosphere soil. Applying biochar will significantly affect the community structure of rhizosphere soil microorganisms, especially fungi. Soil EC, AK, and pH are the main factors affecting the rhizosphere soil microbial community. Together, the results showed that biochar application could improve the physicochemical properties of cotton field soil, thereby affecting the composition and structure of rhizosphere soil microbial communities. The recommended application amount for this experiment is 9 t/hm2 biochar application.