【Objective】Biochar loaded bacteria is a practical application of microbial immobilization. Biochar is considered the ideal carrier of microorganisms in recent years because of its large specific surface volume, pore diameter and good absorbability. Biochar loaded with Bacillus and other exogenous functional microorganisms can increase crop yield, improve root activity, and improve soil enzyme and microbial activity. However, In the process of gradual potassium deficiency, the impact of biochar-loaded potassium-solubilizing bacteria on soil enzyme activity and microbial community structure needs to be further explored. Therefore, this paper aims to explore the effect of potassium-solubilizing bacteria-loaded biochar on soil microbial characteristics.【Method】Based on pot experiment with ryegrass and five treatments: control (CK), chemical potassium fertilizer (KCl), inoculation of potassium solubilizing bacteria (KSB), application of biochar (BC) and potassium solubilizing bacteria loaded biochar (BC-KSB), the change characteristics of soil urease, acid phosphatase, invertase and catalase enzyme activities and microbial community structure were analyzed Also the effects of biochar-loaded potassium solubilizing bacteria composite materials on soil nutrients, soil pH, microbial carbon, microbial nitrogen and ryegrass yield were discussed.【Results】The soil urease and acid phosphatase activity increased first and then decreased while the soil invertase and catalase activity decreased with an increase in the number of harvests for treatments with microbial agents or biochar. . Compared with other fertilization treatments, BC-KSB was more conducive to the increase of soil urease, invertase, acid phosphatase and catalase activities. In terms of soil bacterial community, BC-KSB improved the species diversity and flora uniformity of soil bacteria, increased the abundance of soil beneficial bacteria (Chloroflexi, Actinobacteriota, Bacillus and Bradyrhizobium), and inhibited the reproduction of soil pathogenic bacteria (Proteobacteria and Rhodobacteria). Compared with CK, all fertilization treatments significantly increased the dry weight of ryegrass and BC-KSB treatment showed the largest increase. Also, compared with CK and KCl, BC-KSB treatment can significantly increase the contents of soil microbial carbon, microbial nitrogen, organic matter, total nitrogen and available potassium. However, the content of soil total potassium and total phosphorus in different treatments showed no significant difference. Furthermore, BC significantly increased soil pH compared to other treatments. Redundancy analysis showed that soil organic matter, available potassium, acid phosphatase, urease and microbial nitrogen were the main influencing factors of bacterial community structure, whereas the growth of ryegrass was mainly affected by Burkholderia and Rhodobacteria.【Conclusion】KSB loaded biochar has a positive impact on ryegrass yield, soil nutrients, soil enzyme activity, and bacterial community structure, which provides profound significance for fertilizing soil and improving soil ecological environment.