1. A heating device installable on a camera device, wherein the heating device comprises:a thermal sleeve having a first inner-wall surface and a first outer-wall surface;
a thermally conductive elastomer configured on the first inner-wall surface of the thermal sleeve and disposed between the camera device and the thermal sleeve, wherein the thermally conductive elastomer has an accommodation portion for receiving the camera device and tightly contacts with the camera device; and
a heating sheet configured on the first outer-wall surface of the thermal sleeve and configured to conduct heat to the camera device through the thermal sleeve and the thermally conductive elastomer;
wherein the thermal sleeve is disposed between the thermally conductive elastomer and the heating sheet and tightly contacts with the thermally conductive elastomer.