The comprehensive tripping strategy and quasi three-phase tripping strategy are adopted for the double-circuit transmission lines on the same tower, which may trip all the phases of the double-circuit transmission line during line faults, and result in large-area generator tripping and load shedding of weakly stable systems including wind power and photovoltaic, which worsens the transmission environment of the power grid and seriously reduces the operation stability of the power system. In response to this issue, a quasi two-phase tripping strategy suitable for cross-line grounding faults in double-circuit transmission lines on the same tower is proposed, which can reduce the tripping probability of all phases of double-circuit transmission lines and provide a stable coupling source for the fault phase. Firstly, the topology analysis method is used to establish models for the comprehensive tripping strategy and quasi three-phase tripping strategy of transmission lines, and the impact mechanism of the tripping strategy on fault property determination is analyzed. Secondly, considering the consistency of transmission continuity and fault nature judgment, a quasi two-phase tripping strategy suitable for cross-line faults on double-circuit transmission lines on the same tower is proposed. Finally, the correctness and feasibility of the quasi two-phase trip strategy are verified through PSCAD/EMTDC simulation experiments.