Polypyrrole (PPy) nanoparticles were successfully synthesized from the gelatin solution. PPy nanoparticles with different size and morphology are prepared by changing the preparation conditions including the gelatin concentrations, with surfactant or not. The characteristics of the obtained PPy particles was collected by scanning electron microscopy (SEM), The X-ray diffraction(XRD), Fourier transformation infrared(FT-IR) spectra and Four-probe conductivity meter. The results indicated PPy could form nanoparticles, whereas some bigger spheres occurred when the gelatin concentration is 0.05g/L and the conductivity of the PPy is 0.05S/cm. The possible mechanism was proposed that the gelatin is used as a morphology-directing agent in the polymerization process.