The invention provides a power grid fault positioning method and device and belongs to the technical field of on-line monitoring of power grid faults. Via use of the power grid fault positioning method and device provided in the embodiment of the invention, real time state information of a power grid is collected, a local wiring diagram for an object zone related to abnormal points of the power grid can be determined in a geographical power grid wiring diagram, topology analysis is conducted on the local wiring diagram, failure equipment can be positioned, a fault influence scope can be determined, a fault point can be positioned rapidly and accurately, time needed for on-site troubleshooting can be reduced for overhaul personnel, workers can rapidly respond to faults and make decisions, and a fault influence area can be effectively controlled before expansion of the fault influence scope.