We present a technique for fabricating a fluorescence enhancement device composed of metal nanoparticles (NPs) and porous silicon (PSi) diffraction grating. The fluorescence emission enhancement properties of the PSi and the fluorescence enhancement of the probe molecules are studied on PSi gratings. The fluorescence enhancement of the probe molecules on a fluorescence enhancement device is further improved through the deposition of metal NPs onto the PSi grating. In comparison to metal NP/PSi devices, metal NP periodic distributions can produce a stronger fluorescence enhancement that couples with the PSi grating fluorescence enhancement to achieve an overall three-fold enhancement of the fluorescence intensity.