In order to study the adaptation and effect of microbial flooding after polymer flooding pilot, the test was conducted as pilot project in Ng3 of Zhong1 area. The indigenous microorganisms are first activated and then filtrated; at the same time, 4 strains of functional bacteria are obtained, the bacteria are mass propagated at the reservoir environment, and the crude oil can be emulsified by the microbe. Meanwhile, the physical simulation experiment is studied under the pressure and temperature of the reservoir, and, the result indicates that the oil recovery is enhanced by 7.8%-8.3% by the bacteria. The field test indicates that the microbe is activated and the concentration of metabolism of acetate may reach 105 mg/L. The production dynamic is improved, and the oil recovery is enhanced by 1.27%, and the recovery factor in the pilot is increased by 4.7% to 57.8%.