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针对山火引发输电线路跳闸事故频发的问题，选取了输电线路走廊易于引发线路跳闸的典型植被，利用模拟山火试验平台研究了导线–板间隙在典型植被火焰下的工频击穿特性，通过击穿电压与泄漏电流数据分析了不同植被火焰下间隙击穿特性的差异性，根据间隙的放电机制以及电弧路径发展的图像，建立了火焰条件下间隙放电模型，并对其有效性进行了验证。研究结果表明：植被火焰下间隙的绝缘强度明显下降，特别是在杉树枝火焰下，导线–板间隙的平均击穿电压梯度可降低为纯空气间隙的10%；植被在稳定燃烧阶段的泄漏电流最大，且正半波的泄漏电流值大于负半波，最大可达负半波的十倍左右；在灰烬颗粒影响下，秸秆、茅草等植被在火焰高度较低时，也会导致输电线路跳闸，研究成果可为输电线路在山火条件下的安全稳定运行措施提供参考。“,”Tripping accidents of transmission lines caused by forest fire are frequently. Hence, the typical vegetation which is easily to cause the lines to trip is selected to study the AC breakdown characteristics of conductor-plane gap under fire condition by the simulation forest fire experiment platform. The breakdown characteristic differences of different vegetation flames were analyzed through the data of breakdown voltage and leakage current. According to the discharge mechanism of gap and the image of arc path development, the discharge model of gap under fire condition was established and its validity was verified. Results show that, the gap dielectric strength is decreased significantly under the vegetation flames, especially under the fir branches flame, the average breakdown voltage gradient of gap can be reduced to 10% of that in the pure air gap; the leakage current is maximum when the vegetation is in the stable combustion phase and the value in the positive half wave is much larger than the negative half wave, which can be about ten times than that of the negative half wave; under the influence of particles and ash, the vegetation such as straw and thatch, can also cause transmission line to trip when the flame height is not high. Research results can provide the reference for the safe and stable operation measures of transmission lines under the condition of forest fire.