The invention is suitable for the field of dish-washing machines, and discloses a draught fan drying system of a dish-washing machine. The draught fan drying system comprises an inner container with an inner cavity, a heat exchanger installed outside the inner container and a first draught fan installed outside the inner container. The heat exchanger is provided with at least one cold air flow passage and at least two hot air flow passages. The cold air flow passages and the hot air flow passages are alternately arranged in the heat exchanger at intervals. Inlets of the cold air flow passages are communicated with an air outlet of the first draught fan, outlets of the cold air flow passages and inlets of the hot air flow passages are communicated with the inner cavity, an outlet of at least one hot air flow passage is communicated with the inner cavity, and an outlet of at least one hot air flow passage is communicated with external air. According to the draught fan drying system, air obtained after heat exchanging is carried out through the hot air flow passages is divided into two parts to be exhausted out of the heat exchanger, one part of the air is directly exhausted out of the dish-washing machine, and the other part of the air flows back to the inner cavity again; in this way, bad influences on objects around the dish-washing machine can be avoided, cost is low, and the drying effect and the drying efficiency are also high.