Constant-temperature water circulation structure of hot air circulation oven

The constant-temperature water circulation structure comprises a constant-temperature water tank, the lower surface of the constant-temperature water tank is fixedly connected with a first discharging valve, a heat exchange cylinder is arranged outside the constant-temperature water tank, a backflow pipe is fixedly connected between the heat exchange cylinder and the constant-temperature water tank, and a water outlet valve is arranged on the lower surface of the constant-temperature water tank. A heat flow cavity is formed in the turning position of the backflow pipe and the heat exchange cylinder, and a liquid inlet pipe is fixedly connected between the constant-temperature water tank and the heat exchange cylinder. In the utility model, the contact area between the upper end of the heat exchange pipe and the heat flow cavity is increased through the heat exchange pipe with the upper end screw pitch smaller than the lower end screw pitch, the heating effect is improved, and hot water backflow between the co