Location of lightning point and fault point may be different under lightning stroke fault of transmission lines， because the amplitude of lightning current is tremendous difference. This may influence on precision of traveling wave locating. When lightning wave reflect at the fault point， the distance between lightning stroke and fault points can be calculated with the arrival time difference between lightning wave and reflect wave. Based on fore mentioned analysis， a new approach to locate fault point through the calculation of relative position between lightning and fault points if lightning point is known is proposed. Factors which may affect the fault locating is also discussed. The validity of the methods is proved by EMTDC simulation and confirmation of real example.