An LED unit includes an LED and a lens mounted on the LED. The lens includes a light-incident face adjacent to the LED, a light-emergent face remote from the LED, and a light-reflecting face between the light-incident face and the light-emergent face. The light-incident face includes a first light-incident face which faces the LED, and the light-emergent face includes a first light-emergent face located opposite to the first light-incident face. The first light-emergent face is a continuously curved face which has a curvature firstly increasing gradually and then decreasing gradually along a bottom-to-top direction of the lens.