The hot air circulation oven of Jiangsu Tai'an drying equipment manufacturing Co., Ltd. passes through the air duct to the inner chamber of the oven, and then sucks the used air into the air duct to become the air source for recycling and heating. Ensure the uniformity of indoor temperature. When the temperature value swings due to the action of opening and closing the door, the supply air circulation system quickly returns to the operation state until it reaches the set temperature value.