For studying the mechanism related to the microscopic internal structure of porous carbon additives in lead-carbon batteries, we conducted the electrochemical experiments with a three-electrode system on a lead-doped mesopore-dominated porous carbon (Pb@MC) composite in a Pb2+ containing H2SO4 electrolyte. Through the electrochemical measures, lead particles on the external surface of carbon could be not only electrodeposited into the nano-sized pores of carbon, but also attached on the pore wall with atomic state, which was observed for the first time by using High Resolution Transmission Electron Microscopy (HRTEM) and Aberration Corrected Scanning Transmission Electron Microscopy (ABF-STEM) with the help of ultrathin sectioning. The nano-lead electrodeposits on the internal surface of carbon didn’t grow up because they were confined by the nano-sized pores of carbon. These nano-lead deposits could not only effectively inhibit the hydrogen evolution, but also contribute the pseudocapacitance and enhance the reversible reaction of Pb/PbSO4, and thus result in the longer cycle performance of lead-carbon batteries.