The present invention discloses a negative sequence impedance measurement method. A negative sequence voltage is obtained through injecting a negative sequence current into a power grid, and negative sequence impedance is further obtained. The negative sequence impedance measurement method is able to accurately measure the negative sequence voltage and the negative sequence current so as to accurately calculate the negative sequence impedance of the power grid system. Therefore, the fault analysis of a three-phase asymmetric system may be easily performed, and the fault points may be accurately located. Besides, the obtainment of the negative sequence impedance is helpful for the analysis and the control of the quality of electric energy.