Abstract: Shaking flask and pot experiment were carried out to study the dissolution of feldspar and growth promoting of the plants by the strain NBT of silicate bacterium. The results showed that in agitated flask, at 28℃ for 120 hours , the strain NBT had the ability of releasing 159.1 mg/L of K from feldspar, increased by 226.02% compared with the control treated by sterilized bacterium and the strain NBT could provide the K nutrient for the plants through releasing the K from feldspar under the pot experiment. The effect of K release from feldspar by the strain NBT is similar to both in non sterilized soil and in sterilized soil. The content of mineral K released by the strain NBT accounted for 14.4%～43.1% of K uptake by the plants. However, the mineral K could not be released in the soils inoculated with sterilized silicate bacterium or without silicate bacterium. The effect of K release from mineral K was greatly related to the contents of available K and organic matter in the soil. The soil column experiment showed that lost K from soil inoculated by the silicate bacterium was decreased by 29.6%～56 5% compared with the soil inoculated by the sterilized silicate bacterium. K adsorbed by the capsular polysaccharide of the strain NBT was 31.8%～69.4%of total K. The K uptake was closely related to the strain NBT and its capsular polysaccharide.