Cow dung，as a biological resource with enormous development potential，contains various beneficial microorganisms.Microbial strains with multi-functional growth-promoting effects were screened from cow dung，and their growth-promoting functions were explored through pot experiments on pakchoi，providing excellent strain resources for the development of high-quality microbial fertilizers.Bacterial strains were isolated from cow dung，and their capacity to produce indole-3-acetic acid(IAA)，release potassium，and dissolve inorganic phosphorus was determined.Their species were identified through morphological，physiological，biochemical，and 16S rDNA sequence analysis methods，and their growth-promoting effects were verified through pakchoi pot experiment.A multifunctional growth-promoting strain J9 was selected in the laboratory，identified as Mammaliicoccus sciuri，with IAA production capacity of 36.87 mg/L，potassium release capacity of 35.47 mg/L，and inorganic phosphorus solubilization capacity of 286.11 mg/L. In the pakchoi growth-promoting pot experiment，compared with the control，the soil inoculated with J9 microbial agent showed increases of 4.67%，31.76%，0.28%，13.61% and 12.86% in microbial carbon content，soil respiration，organic matter，alkaline nitrogen，and available phosphorus，respectively.The total root length，root surface area，average root diameter，root volume and root tip number of pakchoi all experienced increases of 8.64%，13.48%，8.70%，21.87% and 11.98%，respectively.The plant height，leaf length，leaf width，expansion degree，aboveground fresh weight，aboveground dry weight，underground fresh weight and underground dry weight of pakchoi exhibited an increase of 13.30%，17.24%，15.00%，36.69%，42.08%，56.52%，48.21% and 33.33%，respectively.The nitrate content in the nutritional quality index of pakchoi was significantly reduced by 36.51%，and the chlorophyll a，chlorophyll b，carotenoids，vitamin C and soluble sugar were increased by 8.00%，11.27%，11.59%，35.00% and 63.90%，respectively.The selected Mammaliicoccus sciuri J9 strain possesses functions of IAA production，potassium release，and inorganic phosphorus solubilization，which coold improve soil fertility and realize the yield improvement and quality optimization of pakchoi.