A polarized projection device includes a light source, a light modulator, and a lens module. The light source is configured for providing a light beam. The light modulator is configured for modulating the light beam into an image. The lens module is configured for converting the image into a polarized image, and includes a polarized prism group, a first polarized module, a second polarized module, a lens, and a half wave plate. The polarized prism group has an incident surface, a light-emitting surface, a first relay surface, and a second relay surface. The image enters the polarized prism group from the incident surface. The first (second) polarized module is disposed off axis at the first (second) relay surface and includes a first (second) reflector and a first (second) quarter wave plate. The lens is disposed at the light-emitting surface. The half wave plate is partially disposed on the lens.