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 . <EOS>