Two cheap byproducts lactic and acetic acid were directly used as the carbon sources of polyhy-droxybutyrate (PHB)-producing recombinant Escherichia coli to investigate the effects of acetic acid and lactic acid on the growth and PHB yield of recombinant E. coli. The PHB synthetic operon phaCAB gene cluster constructed on the basis of Cupriavidus necator genes was cloned into pBAD vector to obtain PHB-producing recombinant strain BL21_pBAD_phaCAB, which was expressed in E. coli by using arabinose as an inducer. The recombinant strain was cultured using LB and M9 medium respectively, and the growth rate and PHB yield were studied to lead the exploration of optimum medium for PHB-producing recombinant E. coli. To explore the effect of lactic acid and acetic acid on the growth and PHB yield of the recombinant strain, 0.04 g/L lactic acid, 1.2 g/L lactic acid, 0.02 g/L acetic acid, 0.6 g/L acetic acid, 0.04 g/L lactic acid + 0.02 g/L acetic acid, 1.2 g/L lactic acid + 0.4 g/L acetic acid were added into M9 medium (containing 2 g/L glucose) as the experimental group where M9 medium (containing 2 g/L glucose) was the control group. The culture media of the 6, 12, 24, and 36 hours were taken respectively to explore the concentration changes in glucose, acetic acid, and lactic acid. The results show that the low nitrogen M9 medium is more suitable for the growth of PHB-producing recombinant E. coli in a low sugar culture environment. After the consumption of glucose, E. coli can use acetic acid and lactic acid as carbon sources for metabolism, and by adding a proper amount of acetic acid and lactic acid, the PHB yield of the recombinant strain can get improved. When 1.2 g/L lactic acid is added, an up to 1.43 g/L PHB yield can be achieved which is 78% higher than the control.