Based on the principle of the decreased ion concentration in aqueous phase resulted from the iodine reaction, the electric conductivity (EC) instrument was used to detect the difference of EC from the reaction solutions thereby PV changes of common edible oils were obtained. The effects of testing temperature, standing time, oscillating time, stability of saturated solution of potassium iodide and types of the oil samples on determination of EC were studied. The PV calibration was established and then validated by iodometry method of Chinese national standards. The results indicated that the experimental conditions had no significant effects on the determination of EC at room temperature (25 ℃), and the calibration of PV was y=15.05x-0.0327, R2 = 0.9961. The validation suggested that the linear correlativity of the determination of PV between two methods was very well, where R2 was 0.9981, and the relative deviation of blind test was less than 10%. The results indicated that the method was effective to determine PV of edible oil.