The invention relates to a process and a device for preparing high-purity rare earth metal by a layer distillation method. The process takes ordinary rare earth metal with a purity of 99 percent as raw material to directly perform distillation purification, or takes rare earth oxide as raw material and metal lanthanum as reducing agent to synchronously finish the reduction and the distillation purification in the same equipment, certain heating rate and vacuum degree are maintained during the reduction and distillation process, and the heat preservation is performed for certain time at a final reaction temperature. The distillation purification process is finished through a layer distillation device, the device comprises an insulating sleeve, a multi-layer baffle, a guide ring, a condensing cover plate, and a supporting ring, an insulating cylinder is arranged on a reduction reactor and is formed by a double-layer heat-resisting metal ring and heat insulating material, and the multi-layer baffle is arranged above the reactor and comprises the supporting ring, a partition and a connecting piece. The condensing cover plate and the supporting ring are arranged on the insulating cylinder and are used to condense and collect the metal. The process and the device are mainly suitable for preparing the purification of metal samarium, europium, thulium and ytterbium, the metal yield is more than 93 percent, and the purity is more than 99.99 percent.