Abstract: In this study, a total of phosphate-solubilizing bacterial colonies were isolated from rhizosphere of Carica papaya. The effects of temperature, pH, shaking speed, inoculum size, liquid volume and culture time on the ability of 4 strains to dissolve phosphorus were studied by single factor experiment and orthogonal experiment. Results showed that under the condition of pH 7.0 and cultured for 5 days, 4 bacterial colonies had best phosphate-solubilizing ability, while the other 4 factors had significant difference in the phosphate-solubilizing. 2 inorganic phosphate-solubilizing bacterium were the same culture temperature and inoculum density, they were 33 ℃ and 3 mL, but the shaker speed and liquid volume were different respectively, they were 180 r/min and 200 r/min, 60 mL and 50 mL. The other 2 organic phosphate-solubilizing bacterium optimal fermentation conditions were the same culture temperature and the same shaker speed, they were 31 ℃ and 160 r/min, but the liquid volume and inoculum density were different, they were 60, 1 mL and 50, 4 mL respectively.