A lamp assembly comprises a lamp cover formed with a plurality of through holes on a peripheral surface thereof. The lamp cover accommodates a positioning element made of a tough material for framing a light-penetrable element therein. The lamp cover fitted with the light-penetrable element allows a plurality of resilient catch elements formed on a periphery of a reflective housing to engage with the through holes formed on the lamp cover at corresponding locations, so that the lamp assembly can be assembled, and have its components rapidly positioned in place, by engaging the components to one another, rather than by screwing with threaded fasteners, thereby simplifying fabrication of the lamp assembly.