The invention provides a projector which comprises a casing provided at least a sheds, a lamp-source apparatus and a heat radiating device arranged in the casing for generating beam. The heat radiating device which comprises a gaseous current conduit tube arranged in the casing and an extractor fan. The two ends of the gaseous current conduit tube is respectively comprises an air-inlet arranged above the near lamp-source apparatus and an air-outlet. The extractor fan is arranged near the sheds of the casing and corresponding to arrange the air-outlet of the gaseous current conduit tube that the hot gas generated by the lamp-source apparatus can be leading-out from the projecting camera through the gaseous current conduit tube. An optical engine is arranged in the casing and connected withthe lamp-source apparatus to form the imagery after processing the beam. The invention can improve the dissipating heat effect and reduce the damage of the fan axis and motor by the hot gas.