The invention relates to a preparation method of a carbon-based composite material for a cathode of a lead-carbon battery, which can prepare a carbon-based lead compound composite material with a controllable proportion, wherein the lead compound uniformly distributes on the surface of carbon material and maintains the original structure character of the carbon material. The preparation method isas follows: the carbon material and a lead ion solution are uniformly mixed in a reaction vessel, a precipitant is slowly dropped, the lead ions are completely deposited on the surface of the carbon material, then filtered, washed and dried to obtain a precursor, and the composite material is obtained through high temperature treatment, and mass ratio of lead compounds is between 1% to 90%. The composite material and the active substances of cathode of lead-acid battery can be better combined by the lead oxide particles on the surface, while the cathode capacity of the cathode of the battery prepared by using the composite material additive is obviously increased, the hydrogen evolution of the cathode is reduced, cathode active material utilization rate is also greatly improved, and the cycle life of high-rate charge-discharge of partial charge state of the cathode is significantly prolonged.