An autostereoscopic projection device includes an illuminating module, a light modulator, an optical module, and a lens module. The illuminating module is for providing light beams having different deflection angles in sequence. The light modulator is for modulating the light beams into compound images in sequence. The optical module is for guiding the light beams provided by the illuminating module to the light modulator, and guiding the compound images to the lens module. The lens module includes a beam splitting prism group, a first spatial filter, a second spatial filter, and a lens. The optical module is disposed at the incident surface of the beam splitting prism group. The first and second spatial filters are disposed at the first and second relay surfaces of beam splitting prism group for filtering the compound images to first and second images in sequence. The second images are different from the first images.