A projecting unit includes a first light-source unit, a first digital micro-mirror unit, a second light-source unit, a second digital micro-mirror unit, a first prism, a first wide-angle lens, and a second wide-angle lens. The first light-source unit is configured to provide a first light beam. The first digital micro-mirror unit is configured to receive the first light beam and transform the first light beam into a first image signal. The second light-source unit is configured to provide a second light beam. The second digital micro-mirror unit is configured to receive the second light beam and transform the second light beam into a second image signal. The first prism is configured to receive and reflect the first and second image signals. The first wide-angle lens and the second wide-angle lens are configured to receive and project the first and second image signals reflected from the first prism respectively.