Abstract: 【Objective】The cultivation parameters of phosphate solubilizing bacteria PSBHY-3 were optimized, in order to provide technical support for its industrial fermentation production of phosphate solubilizing bacteria preparations for aquaculture.【Method】Based on single-factor experiment, the optimal carbon and nitrogen source and their contents for the growth of phosphate solubilizing bacteria for phosphate solubilizing bacteria PSBHY-3 were screened.Then, three significant factors affecting the amount of bacteria were determined with the Plackett-Burman experiment.The optimal level of significant factors was determined with the steepest ascent and Box-Behnken experiment, the regression equation of culture parameters was established.Then the optimal values of the significant factors after optimization and the predicted bacterial amount were obtained.Finally, the validity of the model equation was verified with the shake flask experiments.【Result】The results showed that the optimal carbon source and nitrogen source of PSBHY-3 were soluble starch and peptone-yeast extract(1:1), respectively.The temperature(A), applied amount of yeast extract-peptone(B), and rotation speed(C) were selected as the factor variables, and amount of strain PSBHY-3 was selected as the response variable.The quadratic multiple regression equation was proposed as follow:Y=17.10-0.88A+0.55B+1.27C+0.24AB+0.34AC-0.24BC-3.57A²-2.78B²-6.13C².The optimum fermentation parameters of strain PSBHY-3 were as follows:soluble starch 10.0 g/L, peptone 10.18 g/L, yeast extract 10.18 g/L, sodium chloride 3.0 g/L, magnesium sulfate 1.0 g/L, pH 7, temperature 35.54℃, rotation speed 164 r/min, inoculum quantity 1%, liquid volume in flask 60% (V/V).Under the above optimum conditions, the amount of bacteria was 1.81×10⁹ CFU/mL, which was not significantly different with the theoretical prediction(1.72×10⁹ CFU/mL) (P> 0.05).But it was significantly higher than that cultured by nutrient broth without optimization(1.90×10⁸ CFU/mL) (P< 0.05).【Conclusion】Through single-factor test, Plackett-Burman test, steepest ascent test and Box-Behnken test, the fermentation parameters of strain PSBHY-3 are optimized, which significantly increases the target bacterial amount.The prediction of regression equation is accurate.The optimized fermentation parameters can be used in the industrial fermentation of phosphorus preparation for aquaculture.