This paper focused on a novel microbial polysaccharide as the research subject，using the high-temperature and high-salinity conditions in Shengli oilfield as the basis for experimental design. Based on the Micro-CT scanning results，the micro-channel pattern model was designed by QSGS technology，and the experimental microfluidic model was made by wet etching technology combined with surface modification method. The microbial polysaccharide micro-displacement experiments were conducted in high-temperature and high-salinity environments，and the overall images and microscopic phenomena at various displacement stages were captured，thereby the micro-oil displacement effectiveness of the polysaccharide system in high-temperature and high-salinity heavy oil reservoirs was evaluated. The study demonstrated that the novel microbial polysaccharide exhibited excellent temperature and salt resistance，maintaining high viscoelastic properties under reservoir conditions of 86 ℃ and salinity exceeding 45 939 mg/L，which was significantly improved compared with xanthan gum and met the requirements for injection agents in high-temperature and high-salinity reservoirs. Under the microscopic conditions，the novel polysaccharide could mobilize more clustered residual oil，which gradually transformed into porous residual oil and further into droplet-like residual oil during the displacement process，enhancing the displacement efficiency by 10.15 percentage point when injecting 0.5 PV of new microbial polysaccharide solution with viscosity of 95.6 mPa·s based on water flooding，which was 3.08 percentage point higher than that of xanthan gum. As a pure biological agent，the novel microbial polysaccharide shows promising temperature and salt resistance along with effective performance，indicating its potential application in high-temperature and high-salinity reservoirs and providing a viable technical approach for enhancing oil recovery in such environments.