NOVELTY - Organic silicon modified polyurethane elastomer comprises polyurethane prepolymer, hydroxyl-terminated polybutadiene (HTPB), hydroxy-terminated liquid nitrile rubber (HTLN), polydimethylsiloxane, catalyst, curing agent and solvent. The polyurethane prepolymer is the polyurethane prepolymer of ethers and/or the polyurethane prepolymer of esters. The technological parameters of HTPB are as follows: the hydroxyl value is not less than 0.5-1 mmol/g, manganese is not greater than 2300-4500, the viscosity (40 degrees C, pa.s) is not greater than 1.5-9, the water content % (m/m) is not greater than 0.1, the peroxide (based on hydrogen peroxide)% is not greater than 0.05.    USE - The organic silicon modified polyurethane elastomer is useful for wind blade reinforcement.    ADVANTAGE - The elastomer: has good durability and high elasticity; and has good resistance to weather and hydrothermal stability.    DETAILED DESCRIPTION - Organic silicon modified polyurethane elastomer comprises (in parts by wt.) polyurethane prepolymer (100), hydroxyl-terminated polybutadiene (HTPB) (5-20), hydroxy-terminated liquid nitrile rubber (HTLN) (5-25), polydimethylsiloxane (3-15), catalyst (0.1-10), curing agent (3-10) and solvent (0-30). The polyurethane prepolymer is the polyurethane prepolymer of ethers and/or the polyurethane prepolymer of esters. The technological parameters of HTPB are as follows: the hydroxyl value is not less than 0.5-1 mmol/g, manganese is not greater than 2300-4500, the viscosity (40 degrees C, pa.s) is not greater than 1.5-9, the water content % (m/m) is not greater than 0.1, the peroxide (based on hydrogen peroxide)% is not greater than 0.05. The technological parameters of HTPB are as follows: the hydroxyl value is not less than 1 mmol/g, manganese is not greater than 2300-2500, the viscosity (40 degrees C, pa.s) is not greater than 1.5-2.5, the water content % (m/m) is not greater than 0.1, the peroxide (based on hydrogen peroxide)% is not greater than 0.05. The technological parameters of HTLN are as follows: the nitrile group weight percentage is 5 plus minus 1.5-15 plus minus 2, preferably 10 plus minus 1.5-15 plus minus 2, the hydroxyl value (mmol/g) is not less than 0.4-0.7, preferably not less than 0.55-0.7, the viscosity (40 degrees C, pa.s) is not greater than 8-20, preferably not greater than 12-15, manganese is not less than 2300-3000, preferably not less than 2300-2700. The polydimethylsiloxane is the amino-contained and/or hydroxyl-contained polydimethylsiloxane. The curing agent is triethylene diamine, di(N,N-dimethylaminoethyl)amine, dimethylthiotoluene diamine (DADMT), 3,3'-dichloro-4,4'-diamino-diphenylmethane (MOCA). An INDEPENDENT CLAIM is also included for preparing the organic silicon modified polyurethane elastomer, comprising stirring at a high speed (1000-5000 rotations/minute) under the nitrogen gas atmosphere, reacting the above mentioned composition without curing agent for 3-6 hours at 80-120 degrees C, vacuum removing the solvent and other small molecules, then adding the curing agent, stirring at high speed and mixing, injection molding, pre-curing for 1-2 days at room temperature, and curing for 4-7 days at 55-65 degrees C to obtain the product.