A light guide element for controlling light shape includes a light-incident surface, a light-emitting surface, a first reflecting surface, and a second reflecting surface. The light-incident surface includes a first outer peripheral edge and a first inner peripheral edge. The light-emitting surface includes a second outer peripheral edge and a second inner peripheral edge. The first reflecting surface is constructed by a first profile curve, and connects the first and the second outer peripheral edge. The first profile curve is a connecting line of two points respectively on the first outer peripheral edge and the second outer peripheral edge. The second reflecting surface is constructed by a second profile curve, and connects the first and the second inner peripheral edge. The second profile curve is a connecting line of two points respectively on the first inner peripheral edge and the second inner peripheral edge.