The embodiment of the invention provides an optical assembly, a vehicle lamp and a motor vehicle. The optical assembly includes at least one light source module used for emitting a light beam, a lightpatterning device used for forming a pattern in the cross sections of the light beams, and a reflector with an incident end, an emergence end and a reflective wall extending between the incident endand the emergence end, wherein the light beams passing through the light patterning device enter the reflector from the incident end and are ejected by the reflector from the emergence end, and at least a part of the light beams are reflected by the reflective wall at least once in the reflector.