Abstract: Aiming at the development problems of unsuitable for chemical flooding and thermal recovery enhanced oil recovery for Xin68 Block in Shengli oilfield with deep burial, high temperature and high salt, indigenous microbial flooding technology was developed. First the microbial community structure was analyzed. According to the key research, a long chain carbon source activation system was established. After activation of the bacteria concentration reaching 10⁸ cells/mL, emulsified crude oil particle size was less than 10 μm. The oil displacement experiment shows that oil recovery can be increased by more than 8.5%. Field test has achieved remarkable results, the functional microorganisms were activated, output liquid surface tension was reduced, emulsified oil drops were increased, and viscosity of crude oil was reduced. The oil production per day from 1.0 tons before testing to 1.8 tons, water cut decreases by 14%, the production performances had been significantly improved. The results show that the oil recovery efficiency can be further improved by using endogenous microorganisms.