The invention discloses an additive pouring sealant used for a wind driven generator and a preparation method thereof. The preparation method is characterized by comprising the following steps of: dewatering and blending 100 parts by weight of vinyl silicone oil, 50-200 parts by weight of aluminium oxide filler, 50-150 parts by weight of fire retardant, 0-15 parts by weight of white carbon black, 0-150 parts by weight of processed calcium carbonate, 10-30 parts by weight of alpha and omega-dimethyl polydimethylsiloxane for 30-200 minutes at the temperature of 120-170DEG C and the vacuum degree of 0.06-0.99mpa to obtain base stock; at the constant temperature, taking 100 parts by weight of base stock, adding 1-4 parts by weight of hydrogen-containing silicone oil and 0-0.06 part by weight of inhibitor, stirring in a stirrer for 20-30 minutes to obtain sealant A; taking 100 parts by weight of base stock, 1-6 parts by weight of platinum catalyst and 0.6-2 parts by weight of tackifier, and stirring in the stirrer to obtain sealant B; evenly mixing the sealant A and the sealant B at the mass ratio of 5:1; and solidifying the mixture is solidified at the room temperature to obtain the additive pouring sealant used for a wind driven generator, wherein the additive pouring sealant used for a wind driven generator has the advantages of high thermal conductivity coefficient, excellent electrical property, high and low temperature impact resistance, salt mist resistance, good adhesive property at high temperature and high moisture, and the fire resistance of V-1 level.