In recent years, there have been numerous wildfires caused by various factors, seriously affecting the safe operation of overhead distribution lines. In addition to the contact between overhead lines and trees, human use of fire and lightning are also among the causes of wildfire accidents. The 10 kV overhead line is taken as the research object, and an experimental research platform for single-phase fire-contact and tree-contact faults is built. By means of a high-resistance ground fault model and a comparison in the time and frequency domains, the characteristics of the two faults are analyzed, and the change rules of leakage current flowing through the flame and flame resistance during the flame rise phase of single-phase fire-contact faults are investigated. The results show that single-phase tree-contact faults exhibit smoother amplitude variations during zero-sequence voltage rise compared to single-phase fire-contact faults. Single-phase fire-contact faults display a more pronounced low-frequency component in the zero-sequence voltage compared to single-phase tree-contact faults. During the flame rise phase of single-phase fire-contact faults, the leakage current flowing through the flame exponentially increases with time. The line-to-ground capacitive current has almost no effect on the amplitude of the leakage current flowing through the flame before an arc fault occurs.