The influence of ytterbium on the electrochemical property of PbCaSn alloy in 4.5molL−1 H2SO4 solution is studied by cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and Mott–Schottky plot. The results show that Yb can improve the corrosion resistance of PbCaSn alloy in 4.5molL−1 H2SO4 solution. Mott–Schottky plot reveals that the anodic film on PbCaSn alloy at 1.28VSCE appears an n-type semi-conductive character, Yb can decrease the slope of M–S plot, implying the increment of the defect density within the anodic film, which is beneficial to improve the conductivity of the anodic film. According to the results obtained from EIS, it can be found that the growth of Pb(II) compounds (PbSO4·PbO, 3PbSO4·PbO and PbO) is significantly inhibited by adding Yb.