The invention relates to the technical field of metallurgy and chemical industry, in particular to a preparation method and a use method of a slagging agent for smelting copper dross, which are used for solving the problems that the use amount of the slagging agent is large, the resource recovery rate in a smelting solution is low and the recovery cost is high because the existing slagging agent cannot fully react with the smelting solution. Copper dross is added into a reverberatory furnace to be heated and smelted, then anode slime is added, after the copper dross and the anode slime are smelted, a slag former is added for a reduction reaction, meanwhile, stirring is conducted, liquid-state thin slag is kept, after reduction is finished, standing precipitation is conducted, and upper-layer thin slag, middle-layer lead copper matte and lower-layer high-antimony lead liquid are discharged; according to the using method, molten copper dross and anode slime are reduced through the slag former, smelting sticky slag and non-molten slag are converted into thin slag with good fluidity, tin, copper and high-antimony lead in the copper dross can be recycled in a classified mode through one-time smelting, the copper dross resource recycling efficiency is greatly improved, the service life of a reverberatory furnace is prolonged, and the production cost is reduced. The comprehensive recovery cost of the secondary lead is reduced.