Effect of Bacillus megaterium P17 strain on solubilization of different phosphate rocks was evaluated.Through shaking flask experiment and SEM photos, optimum phosphate rocks for P-solubilizing bacillus P17 strain were screened out.Results showed that bacillus P17 strain could dissolve phosphate rock powders of different sources, especially those from Huangmailing and Huangjinkahuang mines of diagenetic metamorphism phosphorits.After 70 days of culture and 10 times of inoculation, about 81.02% and 78.97% of the total phosphorus in the Huangmailing and Huangjinkahuang phosphate rock powders was solubilized, respectively.Results of the experiment showed that P17 strain could improve the continuous exploitation rate of some phosphate rocks.In addition, after 7 days of culturing, 3.10 mmol L^-1 volatile organic acids and 40.5 mmol L^-1 and 51.1 mmol L^-1 non-volatile organic acids were detected in the medium with Huangmailing and Huangjinkahuang phosphate rock powders as its single phosphorus source, separately;Gas chromatography revealed that bacillus P17 could also generate organic acids, such as lactic, succinic, malic, citric and acetic acids, which can chelate metal ions, thus releasing P from phos-phate rocks.P-solubilization mechanism of bacteria P17 was discussed in this article.