The excess using of chemical fertilizer will be disadvantage to keep the ecological balance and protect environment. Because of long effective, non-pollution, etc, microorganism fertilizer can make up the disadvantages of chemical fertilizer. The key problem of exploitation and using microorganism fertilizer is finds the high effective function strains. Potassium bacterium was a kind of important strains for microorganism fertilizer, it can decompose potassium-bearing minerals of soil for absorbing and utilizing by plants, and often be used in the areas short of potassium. This paper isolated 73 strains of the potassium bacterium from rhizosphere of the Camellia oleifera in the production area of Hunan province by the isolation medium. Mensurated the potassium activity by atomic absorption spectrometry and the results showed that: the strain K50 was the high effective potassium bacteria, the content of the available potassium increased 167.3% compared to the CK. The strain K50 acted as negative in Gram strain, and it can generate the oval spore and the thick capsule. The strain K50 was positive in reaction with dextrose ferment and propionate, and was negative in oxidase aureus injection and V.P. Combined with the sequence analysis of the 16S rDNA, the strain K50 was identified as the Bacillus mucilaginosus. The results will be useful for further study and exploitation of microorganism fertilizer for Camellia oleifera. It can improve the soil composing and micro-ecological environment, and also can decompose the residuum of chemical fertilizer in soil, reduce the environment pollution.