The hydration process of concrete has been studied using a non-contact electrical resistivity measurement. Cement hydration stages have been classified and the hydration mechanism has been interpreted based on the analysis of resistivity development curve and the investigations of microstructure. The proposed concrete conduction model shows that the degree of hydration dominates concrete resistivity. It also proposes some practical applications of the resistivity measurement in the activity evaluation of mineral admixtures, the selection of a superplasticizer and the determination of concrete setting time. A criterion has been proposed for selecting a suitable superplasticizer. The more suitable superplasticizer is the one which gives the mixture a higher Kr and a higher Kt at the saturation dosage. The quantitative relationship between the setting time of concrete measured with the traditional penetration resistance method and the time at which the electrical resistivity critical points occurred has been developed. The electrical resistivty measurement can be used as an alternative method to determine the setting times of concrete.