A heat dissipation device includes a base and a fin set arranged on the base. The fin set includes a plurality of fins each having an undulating body and two flanges extending from the body. The body includes a plurality of peak faces, a plurality of trough faces alternating with the peak faces and a plurality of slanted faces each connecting adjacent peak face and trough face. The peak faces of each fin conform to the peak faces of an adjacent fin, while the trough faces of each fin conform to the trough faces of the adjacent fin. Pluralities of undulating passages are defined between two adjacent fins. Each heat pipe has a first section contacting the base and a second section extending through the fin set. A fan is located corresponding to the passages of the fin set for providing forced airflow to the fin set.