The electrical resistivity and the self-deformation were measured for the cement pastes with a fixed water to binder ratio of 0.4 and different expansive agent replacements of cement (0%, 6%, 10%, and 14%) were used in the pastes.The electrical resistivity and the self-deformation of the pastes increase with expansive agent content after 24h.Based on the test results, the self-deformation were positively correlated to the electrical resistivity after hydration for 24 h.The obtained relationships will help to expand the application of electrical resistivity measurement in understanding mechanism of expansive agent and predicting self-deformation of cementitious hydration system.