A heat pipe includes a step pipe, a mesh, and a supporting component. The step pipe has an evaporating section and two condensing sections. The condensing sections are on the two ends of the step pipe, respectively. The evaporating section lies between the two condensing sections. The inner spaces of the two condensing sections and the evaporating section are interconnected. The peripheral dimension of the evaporating section is larger than the peripheral dimension of each of the condensing sections. The mesh is contained in the step pipe and located inside the evaporating section and the condensing sections. The supporting component is contained in the step pipe and wrapped in the mesh. The combination of these structures increases air's flow rate inside the heat pipe and improves the heat pipe's heat conduction efficiency.