We report a simple method of catalytic deposition of Pb on a gold nanofilm substrate, which was in situ prepared and used as nanocrystal seeds. Due to the unique properties of gold nanocrystal seeds, Pb could be catalytically deposited on the surface of the gold nanofilm. Compared with the deposition of Pb on bare gold electrode, a larger amount of Pb was deposited on the gold nanofilm and the electrical response was amplified significantly. The catalytic deposition of Pb on the gold nanofilm was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. A stable and quasi-reversible redox couple was obtained in neutral solution and studied in detail. The surface of the gold nanofilm could be easily regenerated in 0.1 mol L-1 nitric acid solution. Since the redox peaks of Pb could be effectively separated from those of other metals such as Cu, Cd, and Zn, a selective determination of Pb2+ was achieved. Linear sweep voltammetry (LSV) was used for the determination of Pb2+. The peak currents of Pb varies linearly with the concentration of Pb2+ in aqueous solution ranging from 1.0 to 10.0 mu mol L-1 (R = 0.999), with a detection limit of 0.1 mu mol L-1. It is expected that the gold nanofilm will facilitate the appearance of heavy metal ion sensors with good performance.