The invention provides a switching device for adjusting a lamp installation angle, a lighting device and another switching device. The switching device for adjusting the lamp installation angle comprises a fixed part connected with a lamp, a connecting main body connected with a lamp post, and an anti-loose screw, wherein the fixed part is rotatably connected with the connecting main body by a first screw, the fixed part is provided with an arc-shaped through hole for allowing the anti-loose screw to penetrate through, the connecting main body is provided with a threaded hole, the anti-loose screw penetrates through the arc-shaped through hole to be matched with the threaded hole, and the screwing directions of the anti-loose screw and the first screw are opposite. Compared with the prior art, the switching device for adjusting the lamp installation angle has the advantages that the screwing directions of the anti-loose screw and the first screw are opposite, when external force, such as wind, acts on the switching device, the anti-loose screw and the first screw are stressed by the acting force in the same direction, as the screwing directions of the anti-loose screw and the first screw are opposite, one of the anti-loose screw and the first screw is loosened, while the other of the anti-loose screw and the first screw is certainly tightened, and the switching device is prevented from being loosened and falling off.