In order to select the fault phase in same-tower double-circuit lines， a new fault phase selector is proposed with the analysis on the fault currents in the same phase of double-circuit line. Combining correlation analysis on the same phase currents with the amplitude of fault component， phase selection can be implemented. The algorithm is simple and fast. It can accomplish phase selection rapidly within half cycle. It also has good robustness so that it can be combined with existing distance protection easily. Computer simulation results show that the fault phase selector can solve the phase selection problem of the same-tower double-circuit lines effectively.