The Bohai high-salinity reservoir exhibits relatively high average permeability，while the salt tolerance of ordinary polymers is poor. In order to enhance the salt tolerance of conventional polymers and improve the oil-increasing and water-reducing effects of flooding agents，the effect of sodium silicate on salt tolerance of polymer in high salt reservoir and its mechanism were studied by viscosity and scanning electron microscope test combined with physical simulation evaluation method. The results indicated that the viscosity of the ordinary polymer solution with a mass concentration of 2000 mg/L was 12.4 mPa s lower than that of the salt-resistant polymer solution（32.5 mPa s）under the condition of salinity of 10 206.6 mg/L. Adding sodium silicate to the ordinary polymer solution could increase the viscosity of the system. As the concentration of sodium silicate increased，the viscosity of the 'ordinary polymer + sodium silicate' composite system gradually increased. In different dosing methods，the viscosity of the initial' polymer（2000 mg/L）+ sodium silicate（ 500 mg/L）' system（16.8 mPa·s ）was lower than that of the 'sodium silicate + polymer' composite system（19.6 mPa·s）. However，their viscosities show little difference after shearing. Polymer molecules formed a network structure，while the inorganic gels exhibited a flocculent structure. The "polymer + sodium silicate" system resulted in a denser network framework. With the increase of sodium silicate concentration，the resistance coefficient of the composite system increased，and the residual resistance coefficient increased first and then decreased. The plugging rate of the ordinary polymer system（2000 mg/L）to the core with a permeability of about 6000×10^-3 μm² was only 20%，while the plugging rate of the 'polymer（2000 mg/L）+ sodium silicate（300 mg/L）' composite system to the core with a permeability of about 6000× 10^-3 μm² was as high as 94.3%.