A heat dissipation device for transferring heat generated by a heat-producing element to a heat-dissipating element, includes a graphene plate, a main casing and a supporting plate. The graphene plate, in the form of relatively thin structure, has a first dissipation portion and a second dissipation portion extending from the first dissipation portion. The main casing, generally a planar structure, encloses the graphene plate therein, and has a first dissipation opening exposing the first dissipation portion of the graphene plate. The supporting plate extends integrally from the main casing in order to support the second dissipation portion of the graphene plate. The heat-producing element is inserted through the first dissipation opening in order to mount the same on the first dissipation portion of the graphene plate while the heat-dissipating element is mounted on the second dissipation portion of the graphene plate.