In recent years, forest fires caused by power faults have occurred from time to time. If a ground fault in power distribution is not cut off in time, the fault arc discharge may ignite the surrounding vegetation, thereby leading to a forest fire. A method for dividing the forest fire risk levels (FFRLs) caused by a ground fault on distribution lines (DLs) based on multiple index comprehensive evaluation is proposed in order to carry out forest fire prevention measures in a differentiated manner. This paper analyzes the relevant forest fire risk factors based on the integration of unmanned aerial vehicle patrol data, the historical fault data of DLs, meteorological data and the self-designed experiment of an arc combustion characteristic parameter (ACCP). The weights and risk scores of various forest fire risk factors are determined by a Delphi technique network-analytic process. Then the comprehensive risk score is calculated by weighting and summing the factors. The FFRLs of DLs can be determined. An actual case analysis with a 10 kV DL in the Hunan power grid verifies that the method can divide FFRLs of DLs accurately, clarify the important sections of forest fire prevention and control of DLs, and a powerful reference can be provided for the ground fault disposal device of DLs facing forest fire prevention and control.