Abstract: Alkaline leaching bacteria are new efficient strains for processing alkaline minerals. Slurry gradient domestication and ultraviolet mutagenesis were introduced to improve the adaptive capacity to environment and leaching rate of the strains. With the help of Design Expert-8 software,a three-factor three-level Box-Behnken experiment was conducted to investigate the influence of pulp density,initial bacteria inoculation and temperature on the leaching rate. The optimal experimental condition was determined by Design Expert-8 software and a prediction model was proposed in this paper. Comparative experiment was conducted to investigate the differences before and after this improvement experiment under the optimal conditions. The results show that the improved strain can adapt to the pulp condition better. The population of the improved strain can up to 6. 5 ×10⁸mL^-1 and the leaching rate reaches to 50. 57%,while the population of the original strain can up to 3 ×10⁸mL^-1 and the leaching rate reaches only to 29. 03%.