The invention provides an aluminum bar thermal-processing pretreatment device, and relates to the field of thermal processing. The aluminum bar thermal-processing pretreatment device comprises a mainbody, a workbench is fixedly installed on the left side of the bottom of an inner cavity of the main body, and an impurity removal box is fixedly arranged on the right side of the top of the workbench; a drying box is fixedly arranged in the middle of the top of the workbench, and a grinding box is fixedly arranged on the left side of the top of the workbench; a melting furnace is fixedly arrangedon the left side of the bottom of the inner cavity of the main body, a screw rod is arranged above the inner cavity of the main body, the left end of the screw rod is movably connected with the leftside of the inner cavity of the main body through a bearing base, and a screw rod motor is fixedly installed above the right side of the main body. According to the aluminum bar thermal-processing pretreatment device, a brush is arranged to be matched with the driving of a rotating disc, so that aluminum hydroxide solid outside an aluminum rod is brushed off; and the impurity removal box is arranged to be matched with water inside the impurity removal box, so that the scraped aluminum hydroxide outside the aluminum rod is flushed away, impurities in aluminum materials in the subsequent smelting furnace processing are reduced, and the quality of subsequent products is improved.