A heat dissipation device includes a fin unit (50), and at least a heat pipe (30) including an evaporating section (32) and at least a condensing section (34) extending through the fin unit. The fin unit includes a plurality of fins stacked together. Each fin comprises a wavy and a V-shaped section (52,53) and a planar section (54) therebetween. The wavy and V-shaped sections of the fins can guide an airflow flowing into the fin unit to smoothly flow therethrough, and prevent escape of the airflow from lateral directions of the fin unit. Furthermore, the wavy and V-shaped sections increase the heat dissipation area of the fins and strengthen the fins.