The relationship among the electrical resistivity, chemical shrinkage and autogenous shrinkage is investigated.To quantitatively understand the volume proportions of autogenous shrinkage and volume of empty cavities to chemical shrinkage during the hydration of cementitious materials, the electrical resistivity, chemical shrinkage and autogenous shrinkage are measured for cement pastes with different water to binder ratios and fly ash replacements of cement by weight.A linear equation is established between electrical resistivity and time in logarithmic scale during decelerating period, in which the slope K has a linear relationship with compressive strength at 3 d.The chemical shrinkage and autogenous shrinkage of the pastes decrease with the increasing water-binder ratio or fly ash replacement.The proposed proportion γ,defined as the ratio of the autogenous shrinkage change to the linear chemical shrinkage change after final set, decreases with hydration time due to the increasing strength and elastic modulus of the paste.Autogenous shrinkage is a quite small part in chemical shrinkage when compared with empty cavities formed in the paste.