The precise fault range measurement of the four-circuit line of the mixed tower is difficult because of the coupling between the lines. In this paper, the asymmetric impedance model closer to the actual engineering is introduced, and two impedance decoupling matrices M₁ and M₂ with different physical meanings are introduced. The reverse zero-order g₀ sequence network in the two decoupling modes has the same network topology. The external sequence impedance and the sequence voltage are both 0. The sequence current flows only inside the four loops and is not affected by external devices. Therefore, the g₀ sequence network is uniformly used, and the one-step distance measurement equation is established from the two busbars to the fault point, and the fault ranging of the four-circuit line of the mixed-pressure tower is transformed into a single-sequence network, which greatly simplifies the complexity of the fault location of the four-circuit line of the same tower. A large number of PSCAD/EMTDC experimental simulation data show that both algorithms can achieve accurate ranging, and are not affected by system operation parameters such as fault distance, transition resistance and power angle difference.