A method for forming a pixel of an LED light source is provided. The method includes following steps: forming a first layer on a substrate; forming a second layer and a first light-emitting active layer on the first layer; exposing a portion of an upper surface of the first layer; forming a third layer on the substrate; forming a fourth layer and a second light-emitting active layer on the third layer; exposing a portion of an upper surface of the third layer; and forming a first electrode on the exposed upper surface of the first layer, a second electrode on a portion of an upper surface of the second layer, a third electrode on the exposed upper surface of the third layer, and a fourth electrode a portion of an upper surface of the fourth layer. The first light-emitting active layer and the second light-emitting active layer emit different colors of light.