Disclosed is a tunnel oven, comprising an outer housing (1), an inner housing (2), an air channel (3), a conveyor belt (4), a heat exchanger (5), an air inlet (6), a heat pump system (7), fans (9), a heating device (11), an air flow distributor (12), and an exhaust pipe (14), wherein outside air enters the air channel (3) through the air inlet (6), and the air is pre-heated by the heat exchanger (5) and heated by the heat pump system (7), and the temperature of which is kept constant with the aid of the heating device (11) to heat and dry an object, which is to be heated, on the conveyor belt (4); and hot air is distributed by the air flow distributor (12), some of the hot air being exhausted through the exhaust pipe (14) after heat exchange by the heat exchanger (5), and some of the hot air being mixed with new air which is pre-heated by the heat exchanger (5) and then being heated by the heat pump system (7), then being heated by the heating device (11), heating and drying the object to be heated, and then being distributed by the air flow distributor (12). Recycling heat energy in the air in such a way saves energy and improves heating efficiency. If the temperature in an operation environment is relatively high, the heat pump system (7) can be used to cool the operation environment while heating the air.