A light-emitting device includes a light source, a panel and a light guiding structure. The light guiding structure includes a first light guiding tunnel and a second light guiding tunnel. The first light guiding tunnel includes a first end and a second end. A first opening is formed at the first end and close to the light source. The second light guiding tunnel includes a first end and a second end. The first end of the second light guiding tunnel communicates with the second end of the first light guiding tunnel. A diameter of the second end of the second light guiding tunnel is greater than a diameter of the first end of the second light guiding tunnel. A second opening is formed at the second end of the second light guiding tunnel. A diameter of the second opening is greater than a diameter of the first opening.