Wildfires can cause trips of multiple transmission-lines in a short period and threaten the safe operation of a power grid. The existing key transmission-line evaluation methods are normally based on single factor or subjectively selected factors

thus they are unable to evaluate the key transmission-line under large-scale wildfires comprehensively and reasonably. We put forward a new method for key transmission-line aggregate evaluation based on super efficiency data envelopment analysis. Considering both static operation status and line tripping influence of transmission-lines

we established factors for both two sides

and proposed a new comprehensive key transmission-line evaluation method with multiple factors. We applied the method to a power grid in a wildfire-prone region. The test results show that the method identifies the key transmission-line rapidly and effectively

and thus can provide an auxiliary decision guidance for the safe operation of the power grid.