The invention provides a method for lowering the burning loss of tundish acid-soluble aluminum. The maximum argon blowing amount of non-rippling of the liquid surface of molten steel surrounding long nozzles is used as an argon gas adjusting reference; and in the last stage of pouring, if manipulator vibrating generates mutation or the surfaces of steel slag surrounding the long nozzles ripple suddenly, sliding plates are closed immediately; molten steel tanks descend to the lower rims of the long nozzles at the distance of 90-105 mm from the surface of molten steel, then the sliding plates are opened, and the whole operation of replacing large tanks is completed within 150 s. A covering agent is added when the weight of tundish reaches 35 t or above, it is guaranteed that the surface of the molten steel is free of being exposed, and 300-500 kg of the covering agent is added to each of pouring regions, stopper holes and temperature-measuring sampling holes; then 180-200 kg of the covering agent is added to each of the regions after pouring of each tank begins; and in the pouring process of the molten steel tanks, the liquid level height of the molten steel in the tundish reaches over 1,000 mm, the long nozzles enter the position 300 mm below the liquid surface of the molten steel, carbonized rice hulls are supplemented, and it is avoided that the covering agent on the surface of the molten steel crusts. The burning loss of the tundish acid-soluble aluminum can be controlled to 19 ppm below, the degree of purity of the molten steel is improved effectively, and the quality of casting blanks is improved.