Although fault component current phase selector has excellent performance for single transmission lines， it may select unwanted phase for cross-country faults in double-circuit lines on a same tower. By using the six-sequence fault component， this paper investigates the amplitude and phasor characteristics of fault component current for cross faults of double lines with their phasor comparison equations presented. Based on the results of fault component current phase selector， a kind of synthesis selection scheme， which takes impedance measurement and directional component as supplementary method， is put forward and its flow chart for phase selection is given. Dynamic simulation results by using RTDS show that the synthesis phase selection scheme based on the quantities of single lines at one terminal has better performance for simple faults and cross-country faults of double-circuit lines.