The distribution of power generation centers and consumption centers in China is uneven, necessitating long-distance transmission of electrical energy. As high-voltage transmission technology continues to advance, transmission line corridors are increasingly under pressure and unavoidably pass through areas prone to wildfires. The flames and smoke generated during wildfires significantly degrade the insulation performance of air gaps, leading to potential line tripping and impacting power supply stability. This paper conducted power frequency breakdown tests under wildfire conditions for rod-rod and conductor-ground gaps. The results indicate that flame height and smoke concentration are the primary factors influencing the breakdown characteristics of air gaps. Flame height directly affects the remaining insulation distance in the gap. When the flame bridges the gap, the breakdown voltage decreases by 73% for rod-rod gaps at 1m distance and 75.33% for conductor-ground gaps. Lower smoke concentrations result in less impact on the breakdown characteristics of air gaps. Under smoke conditions, the breakdown voltage for rod-rod gaps decreases in a range of 20%–40%. During smoke bridging, the breakdown voltage for conductor-ground gaps shows a maximum decrease of 59%.