The invention discloses a cobalt smelting waste-based sintered brick and a preparation method thereof, and relates to the technical field of smelting slag resource utilization and innocent treatment. The raw materials used for preparing the sintered brick include cobalt smelting waste, flyash and an additive. The preparation method of the sintered brick comprises the steps of drying and grinding the cobalt smelting waste, the flyash and the additive into dry powder; weighing cobalt smelting waste powder, flyash powder and additive powder at the ratio; mixing and stirring evenly, adding water for wet mixing, ageing and carrying out compression molding; and finally drying and burning to prepare a finished product of the sintered brick. By virtue of recycling smelting slags, the preparation method has good economic benefits and social benefits.