The invention discloses a preheating system suitable for continuous annealing and hot galvanizing and a using method thereof. The preheating system comprises a circulating device and a smoke discharging device, and circulating device is connected to the smoke discharging device; the circulating device comprises a furnace body, jet air boxes, heat exchangers, jet nozzles, circulating air ducts andcirculating fans, wherein the jet air boxes are provided with multiple pairs and are arranged in the furnace body, the multiple jet nozzles are arranged on the opposite surfaces of each pair of the jet air boxes, the corresponding heat exchanger is arranged in each jet air box, and the air injection air boxes on the same side communicate with each other through a waste gas pipeline; the number ofthe circulating fans are multiple, the circulating fans are connected to the inner side surface of the furnace body, and each circulating fan communicates with a pair of the jet air boxes through thecirculating air duct; and the smoke discharging device comprises a smoke exhaust fan, a regulating valve and a smoke discharging pipeline. According to the preheating system and the using method thereof, the heat energy of the tail gas of the radiant tube is fully utilized, so that high-speed jet flow is achieved, strip steel is rapidly and uniformly heated, the capacity of a unit is improved, andthe negative influence on the surface quality of the strip steel is avoided.