Luo 9 Shi 1 block has some problems of high temperature, high viscosity, high water cut and low water flooding efficiency.In order to improve the output of high water cut oil well, the composite system of biological polysaccharide and microorganism was developed. Its temperature resistance, plugging performance, emulsion viscosity role and model of the displacement effect were studied. Finally, the composite system of huff and puff was applied in the field.The results showed that the viscosity of the new biological polysaccharide remained in the range of 120 ~ 125mPa.s at 55 ~ 95℃ and the temperature resistance was strong.When the new biological polysaccharide injected into the core, the pressure increases by 5.6 times and the permeability decreases by 53.3%, which could effectively seal the core.When the ratio of microbial fermentation liquidⅠto microbial fermentation liquidⅡwas 1:2, the high temperature emulsification ability was the strongest and the emulsification viscosity reduction rate was 81.4%. The physical simulation of oil displacement experiment showed that the composite system of biological polysaccharide and microorganism improved oil recovery by 13.9%, which was better than the single system in oil displacement. The application results of five oil Wells showed that four oil Wells had achieved success and the cumulative increase of oil amounted to 2730t. The effect of increasing oil and dewatering was significant, which continued to be effective.It effectively improved the low efficiency of oil well in Luo9 Test 1 block.