A light-emitting diode is provided. The light-emitting diode includes a P-type semiconductor layer, a N-type semiconductor layer, and a light-emitting stack located therebetween. The light-emitting stack includes a plurality of well layers and a plurality of barrier layers that are alternately stacked, the well layers includes at least one first well layer, at least one second well layer, and third well layers that have different indium concentrations. The first well layer has the largest indium concentration, and the third well layers have the smallest indium concentration. Three of well layers that are closest to the P-type semiconductor layer are the third well layers, and the first well layer is closer to the N-type semiconductor layer than the P-type semiconductor layer.