Abstract: Among all biological recovery techniques, microbial flooding presents poor EOR effects and it has always been in the exploration stage for many years. Bio-surfactant has been used for oil recovery for several decades, and the recovery factor by underground-fermentation microbial flooding is generally no more than 5%. In order to improve the laboratory and field application effects of the microbial flooding of surfactant producing bacteria, this paper studied the bio-surfactant synthesis and accumulation rules of the rhamnolipid producing pseudomonas aeruginosa strain Bsw and carried out microbial flooding experiments with the strain Bsw as the core. The oil displacement experimental results of 30 cm square core show that oil recovery technologies impact the oil displacement effects and the underground anaerobic fermentation method can only contribute the recovery factor of 2.83%, while the fermentation liquor method taking advantage of ground aerobiotic fermentation to accumulate the products sufficiently can increase the recovery factor by 15.63%. The effective product accumulated by Bsw strain is the key EOR factor and its function of anaerobic oil degradation makes less contribution to EOR. The research results provide the technical support for biological EOR.