Novel micro/ nanostructures of polyaniline were synthesized via a self-assembly method in the presence of different amino acids, such as tryptophan, lysine, and aspartic acid. It was found that the morphologies, including spinous microspheres, smooth nanospheres, and nanosticks /tubes determined by SEM and TEM images, were related to the kind of different amino acids. The structures of the products were measured by FT-IR spectra and UV-vis spectra.