The invention relates to an automatic thermal insulation device for a hot-mix asphalt mixture transport cart. A direct-current motor is arranged on a rack, the direct-current motor is connected with a belt pulley through a belt, the belt pulley can drive a driving shaft to rotate, the driving shaft drives four sheaves to rotate, steel wire ropes are arranged in sheave grooves, and the steel wire ropes drive driving pulley devices arranged in concave guide rails to move. Because thermal insulation cover supports are fixed to the driving pulley devices and driven pulley devices respectively and a thermal insulation cover is laid on the thermal insulation cover supports, the thermal insulation cover can be controlled to be opened or closed by controlling the rotation direction of the direct-current motor, the thermal insulation cover can be automatically pulled to the front end and the rear end of a compartment from the middle of the compartment to be folded when the transport cart is loaded with materials, and loading is facilitated. After the transport cart is loaded with the materials, the thermal insulation cover can be automatically pulled to the middle of the compartment from the front end and the rear end of the compartment to be unfolded, and thus the thermal insulation function can be achieved. Manual laying and folding of the thermal insulation cover are avoided, labor intensity of personnel is reduced, and potential safety hazards are eliminated.