A light-emitting device, comprising: a reflective shade, which comprises a top end, a bottom end, and a reflector body extending from the top end to the bottom end; a light source, which is located at the top end of the reflective shade and faces the bottom end of the reflective shade, and at least emits lateral light; and a light deflection element, which is located on a light path of the lateral light to collect the lateral light; wherein the light deflection element adjusts the light propagation direction of the lateral light projected on the light deflection element, such that the lateral light exited from the light deflection element is projected onto the reflector body, the reflector body reflects the lateral light projected on the reflector body, and the lateral light exited from the reflector body converges into a light spot of a predetermined size; characterized in that the light emitting device further comprises a first column cylinder and a second column cylinder that allow light transmission, wherein the first column cylinder is nested inside the second column cylinder, the first column cylinder and the second column cylinder are disposed on the light paths between the light deflection element and the reflective shade, an interval is provided between the first column cylinder and the second column cylinder to form an air gap; and in that an outer surface of the first column cylinder is provided with a first concave-convex surface structure, an inner surface of the second column cylinder is provided with a second concave-convex surface structure, an air gap is provided between the first concave-convex surface structure and the second concave-convex surface structure, and the first column cylinder is capable of moving relative to the second column cylinder, thereby changing the shape of the air gap. a reflective shade, which comprises a top end, a bottom end, and a reflector body extending from the top end to the bottom end; a light source, which is located at the top end of the reflective shade and faces the bottom end of the reflective shade, and at least emits lateral light; and a light deflection element, which is located on a light path of the lateral light to collect the lateral light; wherein the light deflection element adjusts the light propagation direction of the lateral light projected on the light deflection element, such that the lateral light exited from the light deflection element is projected onto the reflector body, the reflector body reflects the lateral light projected on the reflector body, and the lateral light exited from the reflector body converges into a light spot of a predetermined size; characterized in that the light emitting device further comprises a first column cylinder and a second column cylinder that allow light transmission, wherein the first column cylinder is nested inside the second column cylinder, the first column cylinder and the second column cylinder are disposed on the light paths between the light deflection element and the reflective shade, an interval is provided between the first column cylinder and the second column cylinder to form an air gap; and in that an outer surface of the first column cylinder is provided with a first concave-convex surface structure, an inner surface of the second column cylinder is provided with a second concave-convex surface structure, an air gap is provided between the first concave-convex surface structure and the second concave-convex surface structure, and the first column cylinder is capable of moving relative to the second column cylinder, thereby changing the shape of the air gap.