A light guide plate includes a main body and trapezoid-like structures. The main body includes a light-incident surface, a first main surface and a second main surface opposite to the first main surface. The trapezoid-like structures are disposed on at least one of the first main surface and the second main surface. The trapezoid-like structures extend along a direction from one side of the main body near the light-incident surface to the other side of the main body away from the light-incident surface. Each of the trapezoid-like structures has a width gradually increasing from one end of the trapezoid-like structure near the light-incident surface to the other end of the trapezoid-like structure away from the light-incident surface. Each of the trapezoid-like structures comprises a flat surface and two side surfaces, and the side surfaces are respectively connected to two sides of the flat surface.