The utility model discloses a double-layer horizontal ball mill which comprises racks, wherein a speed reducer and a motor are arranged on one side of the racks, and are connected with each other. The double-layer horizontal ball mill is characterized in that an outer-layer barrel is arranged between the tops of the racks; a water jacket is arranged on the outer-layer barrel; a cooling water inlet is formed in one side of the outer-layer barrel, and a cooling water outlet is formed in the other side of the outer-layer barrel; an inner-layer steel barrel is arranged in the outer-layer barrel; feed ports are formed in the top centers of the outer-layer barrel and the inner-layer steel barrel respectively; filter holes are uniformly formed in the inner-layer steel barrel; a discharge port and a valve are arranged in the bottom center of the outer-layer barrel; a transverse connecting shaft is arranged on the inner-layer steel barrel; one end of the connecting shaft is connected with the motor through a gear ring and the speed reducer. According to the double-layer horizontal ball mill, a double-layer barrel structure is adopted, and the inner layer is of an unsealed structure, so that the grinding time is further reduced, and energy resources are saved.