A multi-stage tunnel type immersion freezing system is provided. In the freezing system, food products are quickly frozen by passing the food products through a series of divided zones including a precooling zone, a stiffening zone and an immersion zone to eliminate the reduction of freezing effects resulting from the temperature (energy) of the food products, thus achieving high freezing efficiency within a short time. Further provided is a method for quick freezing of food products using the multi-stage tunnel type freezer. The freezer comprises an external refrigerator and external refrigerant exchange means. In the precooling zone, a cold wind at -40 5 o C is blown on the food products using the external refrigerator to precool the food products. In the stiffening zone, a refrigerant is sprayed on the precooled food products to cool the surface of the food products. In the immersion zone, the refrigerant is circulated while maintaining the temperature at -60 ± 5 o C using an external refrigerant circulator to completely freeze the food products.