A heat radiating fin includes a flat body having a front side and a rear side, a plurality of protruded portions formed on the front side of the flat body, and a plurality of recessed portions correspondingly formed on the rear side of the flat body behind the protruded portions. The protruded portions on the flat body of a first heat radiating fin are partially extendable into corresponding recessed portions on the flat body of a second heat radiating fin located before the first one, allowing the first and the second heat radiating fins to be easily and stably stacked.