A heat dissipating device includes a base, a heat pipe disposed on the base, and a plurality of first and second heat dissipating fins. Each first heat dissipating fin includes a fin body having a first through hole for extension of the heat pipe therethrough. The first and second heat dissipating fins are mounted on the heat pipe in a stack and in a spaced-apart alternating arrangement. Each second heat dissipating fin includes a fin body having a second through hole for extension of the heat pipe therethrough, two adjacent lateral edges, and a cut edge interconnecting the lateral edges such that each second heat dissipating fin has a smaller area than each first heat dissipating fin. Thus, the flow field resistance of the heat dissipating device can be reduced to increase the amount of airflow through the heat dissipating device for enhancing the heat dissipating efficiency.