The invention discloses a material off-line hot smoke preheating device and a preheating method thereof, and belongs to the technical field of metallurgy. The device comprises a preheating chamber, a heating unit and a material receiving unit. The preheating chamber is isolated from an electric arc furnace, and the included angle formed between the preheating chamber and the horizontal plane is 30 degrees at least. The method comprises the processes of charging, off-line preheating and recovery. Due to the fact that the preheating chamber and the electric arc furnace are isolated, a furnace body structure, an original production flow and a smelting mode do not need to be changed, and waste heat recovery can be achieved by communicating the electric arc furnace with a pipeline. The device is simple in structure, small in transformation, low in investment and rapid in cost recovering. By controlling smoke, the device is high in safe margin, motility and adaptive capacity.