The invention relates to a molten salt electrolysis cathode educt separating method and device. The molten salt electrolysis cathode educt separating method comprises the following steps that a lump educt is crashed into powder, the powder is conveyed into a sediment tank containing medium liquid, physical separation is achieved according to the different densities of substances, and the medium liquid is heated to volatilize, so that metal powder is obtained. The device comprises the sediment tank, an overflow pipe, a separating medium tank and a backflow pipe, wherein one end of the overflow pipe is communicated with the separating medium tank, the other end of the overflow pipe is communicated with the side face of the sediment tank, a filter is arranged at one end of the backflow pipe and is located in the separating medium tank, the other end of the backflow pipe is communicated with the sediment tank, a pump is arranged on the backflow pipe, and a stirring device is arranged in the sediment tank. By the adoption of the molten salt electrolysis cathode educt separating method and device, metal powder separation is achieved according to the fact that the density of the metal powder is different from the density of an electrolyte, no addition product is generated in the whole process, the environment is almost not affected, and the separated electrolyte can be recycled.