The invention relates to a reflection type bicycle lamp device with an adjustable light projection distance, which comprises a base, a reflecting cover, a luminescence unit and a drive mechanism. The reflecting cover is arranged at the lower surface of the base and is matched with the base to define a containing space and an opening in communication with the containing space. The luminescence unit is arranged at the lower surface of the base and is placed inside the containing space; and downward light rays from the luminescence unit are reflected by the reflecting cover and are projected on a road surface through the opening, and thereby forming an illuminated area. The drive mechanism is used for changing horizontally relative distance between the reflecting cover and the luminescence unit so as to move the illuminated area relative to the base far and near, thus realizing adjustment of light projection distance. The invention has simple design, and a user can select a required mode at any time so that the travel is safer than before.