A method for characterizing a fault in a transmission line network, the method includes the steps of: obtaining a first measured time reflectogram Rm from a signal previously injected into the network, obtaining a second time reflectogram Rs corresponding to the network in the absence of faults, determining the time difference Rref between the first measured time reflectogram Rm and the second time reflectogram Rs, identifying, in the time difference Rref, an amplitude peak characterizing the presence of a fault and its time abscissa indicating the position of the fault, simulating a plurality of time reflectogram hypotheses each corresponding to the network comprising a fault at the identified position, each hypothesis being associated with a different value of at least one parameter characteristic of the fault, selecting the time reflectogram hypothesis closest to the time difference Rref.