Fault location in transmission line plays an essential role in isolating faults. Considering the disadvantage of the single-ended traveling wave method in the fault location of the transmission line, a novel trajectory purification based fault location method is proposed to locate the fault in the transmission line. In the proposed method, the reflected waves and the interference reflected waves at the fault point are firstly recorded with the single-ended traveling wave method to obtain the true or false fault points. Then the location of the predicted fault is acquired based on the ellipse locus diagram of the voltage difference between the two ends of the line against the current at the upstream end (Δv-i). The distance between the estimation and the true or false fault points is further compared, from which the fault point which is the closest to the position of the estimated fault is regarded as the accurate position of the fault. No additional detection devices are required in the proposed method as the voltage or current at both ends of the transmission line can be monitored merely using the existing measurement or protection devices. The proposed method has been validated under the three-phase grounding, single-phase grounding and two-phase grounding of transmission line. The results indicate that the fault location can be accurately located with the proposed method when various types of faults occur in the transmission line.