The reduction processes of PbSO4 with different structures on ph have been studied by the linear sweep voltammetry (LSV) and potential step technique. At high overpotential, the reduction rate of PbSO4 depends on the diffusion of SO42- ions towards hulk solution and Pb2+ ions towards the reaction surface. The large PbSO4 crystals make the diffusion distance of Pb2+ ions to the reaction surface extend, while the small PbSO4 crystals impede the diffusion of SO42- ions through the micropores. The accumulation of PbSO4 without activity occurs in the anodic film. The effects of the H2SO4 concentration and temperature are also discussed.