In view of the shortcomings of existing offshore drilling fluids,this paper optimizes common drilling fluid additives and combines sodium silicate with polymeric alcohols, and developes a high⁃blocking water⁃based drilling fluid with strong inhibition, lubricity and suitable for offshore drilling. The final formulation of seawater sodium silicate polyalcohol drilling fluid is: 400 mL seawater+5.0% bentonite+5.0% Na2CO3+0.4% PAC + 0.7% HA resin + 3.0% sodium silicate + 5.0% polyethylene glycol.The performance evaluation of sodium silicate polyalcohol drilling fluid showed that the apparent viscosity of the drilling fluid system was 30.4 mPa·s, the plastic viscosity was 20.3 mPa·s,the dynamic shear force was 13.1 Pa,and the rheological property was superior to the conventional marine drilling fluid system.The rolling recovery rate of the drilling fluid at 80 ℃ reach up to 87.5%,and the shale swelling height of the 8⁃hour soaking shale is 0.44 mm, which can solve the problem of wellbore stability. The experimental data of the anti⁃pollution ability test indicates that the drilling fluid has the ability to resist salt (Ca2+, etc).