Nanostructures and nanomaterials based on peptide self-assembly have attracted tremendous interests due to the functionalities of peptide molecules. Furthermore, the self-assembled peptide nanostructures are also adopted to fabricate nanomaterials and nanodevices. In this work, the intramolecular folding and self-assembly of a β-hairpin peptide CBHH were first studied under the regulation of platinum ion. And then, platinum nanostructures were synthesized through the reduction of platinum ions templated with peptide self-assemblies. The results of circular dichroism spectroscopy, UV-vis spectroscopy, isothermal titration calorimetry, and atomic force microscopy observation showed that platinum ions could promote the conversion of peptide CBHH secondary structure from a random coil to a β-sheet through coordination with histidine residues. Platinum nanostructures including nanorods and one dimensionally aligned nanorods were synthesized through in situ reduction with CBHH self-assembled nanofiber as the templates. And the synthesized platinum nanostructures showed excellent electrocatalytic activities.