A heat pipe includes a conductive hollow case, a conductive capillary layer, a piezoelectric component, and a flexible component. The conductive hollow case has a first end and a second end. The first end is connected to a heat-generating component. The second end is a heat-dissipating end. The conductive capillary layer is formed on an inner wall of the conductive hollow case. A liquid stored in the conductive capillary layer can be heated to evaporate by the heat-generating component and then move toward the second end. The piezoelectric component is connected to the conductive capillary layer. The flexible component is disposed at a side of the piezoelectric component for being driven by the evaporated liquid so as to exert force upon the piezoelectric component. Thus, the piezoelectric component can generate electric energy, which can be transmitted from the conductive capillary layer to the conductive hollow case.