Palladium nanoparticles were synthesized by the reduction of palladium nitrate through a water bath method in the presence of 12- tungstosilicate with Keggin structure. The morphology, particle size and structure of the palladium nanoparticles were characterized by transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD). In addition, the palladium nanoparticles were used to modify Au electrode. Electrocatalytic properties of nano Pd in hydrazine were studied through the cyclic voltammetry. The result shows that the spherical palladium nanoparticles with the grain diameter about 3~4 nm are obtained. The electron diffraction pattern indicates that the palladium nanoparticles are face-centered cubic polycrystalline. The Pd nanoparticles modified electrodes display excellent electrocatalytic performance for the hydrazine electrooxidation. The oxidation peak current (Ipa) increases almost linearly with the increasing of concentration of the hydrazine at pH=6