Abstract: In order to locate the fault position by the voltage sag monitors, a new fault location method using voltage sag state matching and the positive sequence voltage variation is proposed in this paper. Firstly, a linear programming model is constructed to determine the installation position of voltage sag monitors. It can ensure that voltage sag caused by short-circuit can be monitored in a certain range of fault resistance. Then the fault position is located in two steps: the first is to determine the most probable fault line by state matching; the second is to use the positive sequence voltage variation to construct equation. The equation can solve the specific fault location of the fault line. The simulation results show that the method is of high accuracy and high speed in fault location calculation. It has practical application value.