Abstract: In this passage,the biomass and production of polyhydroxybutyrate(PHB)were studied by controlling different pH values and using pH feedback to control the flow adding mode of medium. According to the experiments of batch culture and different culture medium,the pH feedback medium was confirmed. With this method,400 g/L glucose and 100 g/L yeast dip powder were added to the fermentation process,and the pH of the process was controlled at 6.7~6.9. Under these conditions,the dry weight of Roche alcaligenes sp was 22.52 g/L,and the yield of PHB reached 13.61 g/L. The biomass and PHB yield of Bacillus alcaligenes increased by 12.44% and 5.07%. The results show that PHB can be improved by the pH feedback control medium.