Abstract: The polyaniline/MnT1239 porphyrin/platinum nanoparticle composite was prepared by the cyclic voltammetry electrochemical polymerization of polyaniline/MnT1239 porphyrin composite materials, and the reduction potentiostatic deposition of platinum nanoparticles. Significant changes appeared the polyaniline/MnT1239 porphyrin material after the electrodeposition of platinum: the average diameter of the rod-like structures increases from 90 nm to 200 nm, a large specific surface area, and good spatial loadable ability. The average size of platinum nanoparticles is 20 nm, with homogeneous distribution and great electrical conductivity.