In order to screen bacteria with strong potassium-dissolving activity, and to alleviate soil potassium deficiency, five strains of potassium bacteria ( SK1-7, SK2-3, SK2-7, SK3-3, SK3-10) with strong potassium-dissolving activity were isolated and screened from forest soil. SK1-7,SK2-3,SK2-7,SK3-3, SK3-10 were identified as Bacillus aryabhattai, Ensifer adhaerens, Klebsiella singaporensis,Microbacterium maritypicum and Raoultella ornithinolytica respectively by morphological,physiological and biochemical experiments and 16S rRNA gene sequence analysis. Potassium ion contents in fermentation filtrate of the 5 strains of potassium-solubilizing bacteria were 42.70,50.40,49.70,41.50,45.23 μg/mL,respectively after 7 days of incubation in the medium,and the pH values of fermentation filtrate were also significantly reduced. The growth-promoting test of 5 strains of potassium-solubilizing bacteria on tomato showed that,the fermentation filtrate of SK1-7,SK2-3,SK2-7 could improve the germination rate of tomato seeds significantly or extreme significantyl.Tomato plant height,fresh weight and dry weight increased after treatment of tomato plants with SK1-7,SK2-3,SK2-7 for 40 d.Biological activity difference tests showed that 5 strains of potassium-solubilizing bacteria could secrete IAA;the fermentation filtrate of SK2-7 and SK3-10 had antibacterial effects;SK1-7 exhibited stronger ability of secreting protease.