A heat dissipation device includes a base, a first fin unit and two second fin units arranged on the base. The base has a substrate and two parallel heat spreaders extending integrally and perpendicularly from the substrate. The first fin unit is arranged on the substrate and sandwiched between the heat spreaders. A plurality of first channels are defined in the first fin unit and parallel to the heat spreaders. Each of the second fin units is perpendicularly arranged on the substrate and located at a lateral, outer side of one of the heat spreaders. A plurality of second channels are defined in each of the second fin units and extend along a different direction compared to that of the first channels.