A heat dissipating device for lightings includes a light source module, a heat sink, and a converter. The heat sink has a substrate and a plurality of heat dissipating fins extending outward from the substrate. A plurality of channels is formed between the heat dissipating fins. Insides of the channels respectively have a port open to the centre of the heat sink. Thereby, the channels of the heat sink can effectively direct the airflow into the centre of the heat sink, enhancing the heat dissipating effect of the heat sink.