An installation assembly of a ceiling lighting fixture, a ceiling lighting fixture and a ceiling lamp are provided. The installation assembly includes a fixing base and a connecting base detachably connected with the fixing base. One of the fixing base and the connecting base is provided with a snap recess, and the other of the fixing base and the connecting base is provided with an elastic buckle which is capable of being snap-fitted with the snap recess. The elastic buckle has a guide slope, the elastic buckle is capable of being compressed as the connecting base moves toward the fixing base, and being introduced into the snap recess through the guide slope. The elastic buckle is rotationally fitted with the snap recess, and the snap recess is provided with an avoidance notch for the elastic buckle to be detached.