A folding protective cover structure is used to cover and protect a heat-conductive medium disposed on the bottom surface of a heat sink device. An unfoldable plate body is employed and has a hollow portion, a folding portion, and an adhesive area; wherein the hollow portion is used for surrounding the heat-conductive medium with a frame-fixing plate extending from its edge, which is folded towards an opposite direction of the heat-conductive medium, so as to keep an upright state; the folding portion is folded towards the hollow portion, so that the frame-fixing plate passes through the folding portion to clip and fix the folding portion, thus forming an accommodating space for protecting the heat-conductive medium; and the adhesive area is located at the edge of the hollow portion, facing the surface of the heat sink device, for adhering and securing the plate body to the heat sink device.