The invention provides an auxiliary heat preservation device for a pet dog. The auxiliary heat preservation device comprises a pet box, two storage cylinders which are horizontally arranged on the twoside faces inside the pet box respectively, two driving shafts which horizontally penetrate through the centers of the two storage cylinders respectively, pet quilts arranged on the two driving shafts, driving mechanisms arranged at the two sides of the pet box, crease-prevention mechanisms arranged at the two ends of the two storage cylinders respectively, conveying mechanisms arranged on the two storage cylinders respectively, first power mechanisms connected with the driving mechanisms and second power mechanisms connected with the conveying mechanisms; the auxiliary heat preservation device further comprises an infrared sensor arranged in the pet box, and the infrared sensor is connected with the first power mechanism and the second power mechanism separately through an audion amplification circuit and a relay. By means of the auxiliary heat preservation device for the pet dog, the situation that creases are easily generated in the process of releasing and retracting the pet quilts is avoided, and the using flatness of the pet quilts is guaranteed.