A projection device, including a light source module and a color wheel, is provided. The light source module includes a plurality of solid-state lighting sources driven by a DC drive power to sequentially provide a first light generated by a first number of light sources, a second light generated by a second number of light sources and a third light generated by a third number of light sources within a response cycle, wherein the number of light sources to be turn on is less than or equivalent to a total number of solid-state lighting sources. The color wheel has a first block, a second block and a third block, respectively corresponding to the first to third lights, so that the projection device sequentially outputs a first color light with a first brightness, a second color light with a second brightness and a third color light with a third brightness.