Abstract: Crevice cathodic polarization characteristics of Q345E steel in NaCl solution were studied by a rectangular crevice model, especially in the influences of polarization time, polarization control potentials, crevice thicknesses and concentration of NaCl solution on polarization potential and polarization current density. Results show that the polarization potentials and polarization current densities in crevice from top to bottom were gradually decreased with polarization time. When the polarization control potentials shifted to negative with the growing of crevice opening size, the polarization potentials gradually decreased but the polarization current densities increased. Reducing the concentration of Cl- in solution, the polarization potentials of the samples in different positions of crevice increased but the polarization current density decreased.