There are some problems of high temperature，high viscosity，high water cut and low water flooding efficiency in Luo 9 Shi 1 block. In order to improve the output of high water-cut oil well，the composite system of microbial polysaccharide and microbial fermentation broth was developed. Its temperature resistance，plugging performance，emulsion viscosity reduction and oil displacement efficiency were studied. Finally，the composite system was applied on this block. The results showed that the viscosity of new microbial polysaccharide remained in the range of 120—125 mPa·s all the time from 55 ℃ to 95 ℃，indicating strong temperature resistance. When the new microbial polysaccharide was injected into the core，the pressure increased while the permeability decreased by 53.3%. It could effectively seal the core. The microbial fermentation broth was composed of fermentation broth I mainly contained rhamnolipid biosurfactant and fermentation broth II mainly contained sugar-protein-lipid biological emulsifier. When the volume ratio of Ⅰ to Ⅱ was 1∶2，the emulsification ability at high temperature of microbial fermentation broth was the strongest. The rate of emulsification viscosity reduction to oil was 81.4%. The physical simulation of oil displacement experiment showed that the composite system of microbial polysaccharide and microbial fermentation broth had improved oil recovery by 13.9 percentage points，which was better than that of single system. The application results of single well huff-and-puff showed that four oil wells had the significant effect of increasing oil and dewatering with the cumulative oil increase of 2730 t. It effectively improved the low efficiency of oil well in Luo 9 Shi 1 block.