A decorative lighting device, adapted to be installed onto wheel rim of vehicle, includes a telescopically fixing mechanism and a light-emitting assembly connected thereon. The light-emitting assembly includes a lid plate and a plurality of light-emitting units fixed thereto. The telescopically fixing mechanism includes a support seat, a clipping-and-abutting plate connected fixedly to the support seat, a plurality of telescopic links, one end of each of which is accommodated between and pivoted to the support seat and the clipping-and-abutting plate, and another end of each of which is wedged by being fixed in a central hole of the wheel ring when extended outwardly, and a rotating wheel pivoted to the support seat and capable of driving the telescopic links to make actions of shrinking inwardly or extending outwardly. Thereby, it is possible to simplify the manner of installing a decorative lighting device or a light-emitting assembly onto a wheel rim, without doing any machining process thereto.