A heat dissipation device includes a heat conducting plate and a heat sink. The heat conducting plate has a first surface and a second surface opposite to each other. The heat sink is coupled to the first surface of the heat conducting plate. The heat sink includes a first peak portion, a second peak portion, a valley portion and a first curved surface. The first peak portion and the second peak portion are adjacent to each other. The valley portion is located between the first peak portion and the second peak portion. The first curved surface is coupled between the first peak portion and the valley portion. An extension line perpendicular to a corresponding tangent line of the first curved surface passes between the first peak portion and the second peak portion.