The invention provides a method for reducing alloy cost during smelting of oriented silicon steel in an RH refining furnace. The method includes the steps that when the temperature of molten steel is larger than 1615 DEG C, and the oxygen content is larger than 500 ppm, high carbon ferromanganese is added at the early stage of decarburization treatment. By adopting the method, the alloy cost can be reduced, if the RH in-position temperature of a converter is larger than 1615 DEG C and the [O] is larger than 500 ppm, the oxygen content can also be reduced to a certain extent, the situation that the steel feeding temperature is too high is avoided, the molten steel temperature of an RH supply casting machine is stabilized, and the purpose that the casting machine performs stable and continuous pouring is achieved.