Light guide plate and light source device

The utility model relates to a light guide plate and a light source device. The light guide plate has a first direction and a second direction which are vertical to each other, and comprises a first optical microstructure and a second optical microstructure, wherein the first optical microstructure is arranged in a visible region of the light guide plate, and extends in the first direction; the second optical microstructure is arranged in at least a part of a transition region adjacent to at least one incident surface of the light guide plate, and extends in the second direction; the transition region is adjacent to the visible region; and the surface of the visible region, with the first optical microstructure, of the light guide plate forms a step with the surface of the transition zone, with the second optical microstructure, of the light guide plate. The light guide plate and the light source device have the advantages that: the light-emitting uniformity of the light guide plate can be improved; in additi