The invention discloses a transmission line double-end traveling wave fault ranging method based on an overdetermined equation set. The method comprises the steps of constructing an overdetermined equation set first; then measuring the time when an initial traveling wave signal generated by a fault point arrives at a line measuring end M and the time when the initial traveling wave signal generated by the fault point is reflected to the line measuring end M by a line measuring end N; measuring the time when the initial traveling wave signal generated by the fault point arrives at the line measuring end N and the time when the initial traveling wave signal generated by the fault point is reflected to the line measuring end N by a line measuring end M; and calculating the position of the fault point by adopting the overdetermined equation set according to the four times. The position of the fault point for eliminating the influence of wave speed is solved by measuring the time when the initial traveling wave generated by the fault point arrives at the two measuring ends of the transmission line, the line measuring end M reflects the traveling wave to the measuring end N and the linemeasuring end N reflects the traveling wave to the measuring end M, thereby reducing the measurement error and improving the ranging precision.