In order to study the relationships between the resistivity and the salinity of chloride saline soil and of sulphate saline soil with different salinity under the condition of saturation state, the resistivities of chloride saline soil and sulphate saline soil with different salinity are tested. Through data fitting, a fitting formula of the resistivities of chloride saline and sulphate saline and the variation of salinity are obtained under the condition of saturated state. Compared with their resistivities the results show that the resistivity of chloride saline soil is bigger than that of sulphate saline soil under the condition of saturation state with the same salinity and output voltage, so is the rate of current change. This study is a salutary lesson for the research on electro-osmosis method for saline soil treatment.