A projection device includes a projection lens, a first laser light source, a second laser light source and a polarization direction. The first laser light source and the second laser light source respectively emit a first laser light to the projection lens through a laser optical path, wherein the first laser light has a first polarization direction. The polarization direction conversion layer is disposed on the laser optical path and configured to convert the first laser light of the first laser light source into a second laser light, wherein the second laser light has a second polarization direction different from the first polarization direction.