A light source module of a photo printer includes a first micro light source, a second micro light source, a rod lens array and a microlens. The first micro light source emits a first light beam. The second micro light source emits a second light beam. The rod lens array is arranged between the first micro light source, the second micro light source and a film paper. The microlens is arranged between the first micro light source, the second micro light source and the rod lens array. The microlens is used for converging the projection angles of the first light beams and the second light beam. The microlens has an optical axis. The second micro light source is arranged along the optical axis. The first micro light source is arranged beside a first side of the optical axis.