The electrical resistivities of the cement pastes with the different polycarboxylate superplasticizer dosages were examined and analyzed. The relationship between the occurring time of minimum resistivity and the initial setting and final setting times was established. The study results show that the relation between the resistivity of cement mortar at early age and the compressive strength of its corresponding age is a linear correlation, that measuring the rsistivity may predict the strength of hardened cement, and that the resistivity curve can reflect the process of hardenability of paste.