AFM and PL are adopted to study the morphological and photoluminescent characteristics of a series of porous silicon (PS) samples etched with direct current and pulsed current.The results of AFM indicate that there are many “hillocks” at the surface of PS samples and the microstructure of PS samples is quite different with different etching modes.The amount of the small Si particles formed by pulsed etching is more than that by direct current etching under the-equivalent etching-conditions and the particles appear more protruding and sharper by the pulsed etching.Moreover,PL spectra shows that it is easier to get photoluminescent PS samples with higher intensity by using pulsed etching method.The microstructure of PS samples plays a very important role in the generation of photoluminescence of porous silicon.