The fabrication of one-dimensional (1D) Fe3O4-PPy nanocomposites was successfully accomplished by using an anodic aluminum oxide (AAO)-mediated vapor deposition polymerization (VDP) method via a one-pot route. The observation of the Fe3O4-PPy nanocomposites confirmed that the morphology of the products was influenced effectively by the size of the AAO template, and the in situ formation procedure effectively prevented the aggregation of Fe3O4 nanoparticles with ca. 3 urn diameter.