A lamp assembly includes a light module and a stem. The light module includes a reflector, a first fixing plate, a second fixing plated mounted on the first fixing plate and having a plurality of fixing pieces pivotally connected thereon for fixing the reflector between the first fixing plate and the second fixing plate, and a lamp. By rotating the fixing pieces, the reflector is easy to replace. The stem includes a plurality of connecting tubes and connecting assemblies. Each connecting assembly has a male joint with an L-shape projecting and a female joint with an L-shape slot. The male joint is fitted into the connecting tube, and the female joint is fitted into another connecting tube. By engaging the L-shape projection with the L-shape slot, the two connecting tubes can be connected without twisting a wire inside the stem.