This paper proposes a novel approach of transient-based faulty phase selection for double circuit lines on the same tower. This phase-selection algorithm uses the wavelet transform to extract the transient energy of current faulty component in each phase and takes the transient energy as phase selection criterion. First, according to the fault equivalence principle of the single line and double circuit lines on the same tower, this approach identifies the fault phase preliminarily. Then the transient energy magnitudes are compared to select the same-name-phase fault lines and further identify the fault phase precisely. At last, this paper presents a complete faulty phase selection based on the single terminal quantities of double circuit lines. The effectiveness of the approach has been verified by simulating different fault types, fault location, fault time and different transition resistance with PSCAD/EMTDC.