New fault phase selector of protective relay for double circuit lines is proposed. There are many problems for ordinary fault phase selector used on double circuit lines， which have been researched based on experimentation results and theory analysis. This paper starts with the different characteristics between simple line faults and crossing-line faults. The new method for identifying simple line faults and crossing-line faults is put forward. After a fault occurs， the protective relay will make use of the relation between zero sequence current and zero sequence voltage to identify the fault types above all. Different fault phase selecting schemes are used in simple line faults and crossing-line faults. The problems mentioned in front are solved commendably.