A heat dissipation device includes a heat absorbing member, a number of fins mounted on the heat absorbing member, a first connecting pipe, and a second connecting pipe. A top surface of the heat absorbing member defines a serpentine slot. The slot includes an inlet hole and an outlet hole communicating with two opposite ends of the slot and extending through the heat absorbing member. The first connecting pipe is connected to the inlet hole of the heat absorbing member, and the second pipe is connected to the outlet hole of the heat absorbing member.