A compact reflector fluorescent lamp unit includes a lamp cap, a lamp tube, an electronic ballast assembly, a circuit board, a housing, an intermediate plate, a reflection cup, and a transparent plate. The intermediate plate and the housing, the intermediate plate and the circuit board, and the intermediate plate and the reflection cup are tightly assembled together. The reflection cup is connected to a lower surface of the intermediate plate and arranged independently underneath the housing, and has an internal surface having a high degree of fineness, and an external surface having a high degree of roughness by frosted finishing, thereby allowing the radiation heat generated through the body of the reflection cup to be dissipated by the external surface.