Contamination can change the physical properties of soil, reduce the strength of cemented soil foundation, and then induce the instability or disruption of buildings. This study explored the relationships among the age, electrical resistivity, unconfined compression strength, contamination of municipal sewage concentration. Firstly, we mixed the silty clay with municipal sewage of five different concentrations to form the contaminated soil. Then, mixed the contaminated soil with ordinary portland cement to form the cemented soil blocks. Finally, measured the unconfined compression strength and electrical resistivity of these blocks. The results show that the unconfined compression strength and electrical resistivity increase linearly with the increase of the logarithm of age, and decrease exponentially with the increase of municipal sewage concentration. The unconfined compression strength of cemented soil has a linear relationship with its resistivity. The municipal sewage concentration and age can be use to predict the unconfined compression strength of cemented soil.The predicted values correlate well with the experimental values.