A light-guide optical element is provided, including a transparent light-guide body having a first inclined surface and a second inclined surface disposed therein. The transparent light-guide body includes a side surface facing a first direction, and a first surface and a second surface which are adjacent to the side surface and face each other. The first inclined surface extends from the first surface to the second surface. The second inclined surface is located at the other side of the first inclined surface facing the side surface. The second inclined surface extends from the first surface to the second surface. When an input light enters the transparent light-guide body, the input light is partially reflected by the first inclined surface and the second inclined surface to form an output light output from the transparent light-guide body.