The utility model relates to a hot air device, which comprises an air blower (10), an air heater (8) and a hot air gun (4). An air outlet of the air blower (10) is connected with the air heater (8) through a flexible pipe (9), and an air outlet of the air heater (8) is communicated with the hot air gun (4). The hot air gun (4) comprises a primary pipe (401) and at least two derivate branch pipes of the primary pipe (401), and the primary pipe (401) is in seal connection with the air outlet of the air heater (8). Each branch pipe comprises a rigid pipe section (408) fixedly connected on the primary pipe (401), a gun opening (405) for discharging air to heat strip materials (3) and a flexible pipe section (403) for connecting the rigid pipe section (408) and the gun opening (405). The hot air gun is provided with the flexible pipe section, and the position of the gun opening can be adjusted according to the positions of the strip materials and the pipe materials, thereby enabling the air out of the gun opening to heat the strip materials and the pipe materials better and reducing the loss of heat.