Four species of photosynthetic bacteria, which are selected and preserved in the laboratory, are cultured in VB₁₂ wastewater. Maximal specific degradation rate (Umax,COD) is defined to compare the degradation capabilities of photosynthetic bacteria. The study indicates that the second one''s maximal specific degradation rate, which is the highest, is 0.698g COD/(h·g PSB). The second one''s degradation kinetics is also studied. The research provides the suitable means to choose the best photosynthetic bacteria for VB₁₂ wastewater treatment.