A light-emitting device comprises a substrate, an epitaxial structure formed on the substrate including a first semiconductor layer, a second semiconductor layer, and a light-emitting layer formed between the first semiconductor layer and the second semiconductor layer. A trench is formed in the epitaxial structure to expose a part of side surface of the epitaxial structure and a part of surface of the first semiconductor layer, so that a first conductive structure is formed on the part of surface of the first semiconductor layer in the trench, and a second conductive structure is formed on the second semiconductor layer. The first conductive structure includes a first electrode and a first pad electrically contacted with each other. The second conductive structure includes a second electrode and a second pad electrically contacted with each other. Furthermore, the area of at least one of the first pad and the second pad is between 1.5×104μm2 and 6.2×104 μm2.