The invention discloses a preparation method of ultrafine lead powder. The ultrafine lead powder is prepared by burning organic acid lead. The burning method comprises two phases: in the first phase, lead citrate is cracked in an anoxic atmosphere, the cracking products are PbO and carbon; in the second phase, the cracking products in the first phase are oxidized in an oxidizing atmosphere to generate the ultrafine lead powder, which comprises PbO, Pb, and residual carbon. The mass percentage of lead in the ultrafine lead powder is less than 30% and the mass percentage of residual carbon is 0.1 to 1%. The provided preparation method has the advantages that the Pb content in prepared ultrafine lead powder, uniformity of particle size of lead powder, and carbon content of lead powder can be effectively controlled. The particle size of prepared ultrafine lead powder is less than 200 nm, the particle size is uniform, and residual carbon is positive to negative pole and positive pole of battery. The prepared ultrafine lead powder has a wide application prospect in the field of high performance lead-acid battery.