Abstract: An illuminating device with adjustable light beams and a method for assembling the same. The light-emitting units are disposed on the substrate. The optical element is disposed in the path of a light emitted by at least one of the light-emitting units. The driving unit drives a first or second set of the light-emitting units, wherein a light beam formed by light that is emitted by the first set of the light-emitting units and passes through the optical element has a different shape or projection angle from a light beam formed by light that is emitted by the second set of the light-emitting units and passes through the optical element.