This paper proposes a new fault location algorithm to accurately locate the faults of seriescompensated double-circuit transmission line and improve the stability of power system operation, which is not affected by fault types. The proposed algorithm is based on asynchronous voltage and current at both ends of the line, the pre-fault voltage and current are used to synchronize time. The six-sequence component transformation is introduced, and with the help of the phase-sequence selection rule, the proposed algorithm eliminates the non-linear impedance of metal oxide varistor (MOV). Simultaneously, to confirm the robustness of the algorithm, different fault types, different fault initial angles and different fault resistances are taken into account in the system simulation. Not only that, the influence of series capacitors (SCs) installation positions, line parameter errors, different sampling rates and measurement errors are also tested. In general, the proposed fault-location algorithm has excellent performance. PSCAD/EMTDC and MATLAB are used in simulation studies, the results show that the maximum estimated error of faultlocation does not exceed 1.8631%.