Abstract: Zinc ribbon mitigation lines are an important measure for reducing the alternating current (AC) interference level of buried pipelines. At present, there is a lack of research on the effective length of zinc ribbons and the distribution law of leakage current density. To provide guidance for the design of zinc ribbons in AC interference mitigation, an AC interference calculation model was established. Through numerical simulation, the distribution laws of zinc ribbon leakage current under different conditions such as zinc ribbon length, soil resistivity, zinc ribbon line resistance, pickup current, and current inflow point were explored. In addition, the main reasons for the existence of the effective zinc ribbon length were analyzed using the equivalent circuit of zinc ribbon leakage current. The results show that when the length of zinc ribbon was 100 m, as the soil resistivity increased from 20 Ω·m to 300 Ω·m, the effective length of zinc ribbon increased from 61 m to 72 m; as the zinc ribbon line resistance decreased from 7 Ω/km to 3 Ω/km, the effective length of the zinc ribbon increased from 61 m to 68 m; when the zinc ribbon length increased from 100 m to 500 m, the effective length of zinc ribbon increased from 61 m to 87 m.