A light guide plate disclosed in the present disclosure includes a board body, a prism component and at least one optical microstructure. The prism component is disposed on at least one surface of the board body. The at least one optical microstructure is disposed on a top end of the prism component. The optical microstructure includes a first light guiding unit and at least two second light guiding units. A first angle is formed between two inclined surfaces of the first light guiding unit, and the first angle is substantially between 45˜60 degrees. The second light guiding units are symmetrically disposed on opposite sides of the first light guiding unit. A second angle is formed between an inclined surface and a bottom surface of each second light guiding unit, and the second angle is substantially between 10˜60 degrees.