A document camera and its light box are provided in the disclosure. The light box includes a base, a light guiding plate embedded in the base, and a light source device movably disposed on the base. The light guiding plate has a light input face and a light output face which are both light transmissive from the base. When the light source device is moved to face the light input face, the light source device provides lights outwards the light guiding plate via the light input face, otherwise, when the light source device is moved away from the light input face, the light source device provides light to the light output face down wards.