Six 0.3 ha earthen ponds were divided into three groups. We regularly added photosynthetic bacteria and nitrifying bacteria to group A, and regularly added yeast and lactic acid bacteria to group B, but added nothing to group C which was served as control. Throughout 12 weeks culture period, group A got the best growth rate, the best yield of 572 kg/pond and the best survival rate of 73% at harvest. However, group B got the worst yield of 239 kg/pond and the worst survival rate of 58%. Water quality of the shrimp ponds have following features during experimental peried : 27.0-33.0°C water temperature, 26-101 cm transparency level, 7.94-9.56 pH level, containing 4.72-8.44 mg/l of dissolved oxygen, 0.05-3.81 mg/l of ammonium-N, 0.004-1.185 mg/l of nitrite-N, and a level of 20.5-40.5 ppt salinity. As to bacterial flora, the results showed we can see that photosynthetic bacteria and nitrifying bacteria can live well in Penaeus monodon ponds, but yeast and lactic acid bacteria can’t.