Precise fault location is an important precondition of quick power supply restoration after transmission line fault occurs.In generally,concerning one-phase to ground fault,it is the transient resistance that causes that the impedance from where the relay is installed to where the fault occurs is caculated incorrectly.On such scenario,a double-ended fault location algorithm is preferred in order to acquire rather precise fault location result.Based on analyzing the source of additive impedance,this essay presents that under some special working conditions whereas double-ended fault location becomes invalid,single-ended fault calculation based on solving triangle calculation gives precise results.And this method can also be applied to hybrid parameter transmission lines which have both overhead lines and cables.The simulation and field data verified that the method has high precision.