The invention discloses a method based on the ferromagnetic resonance overvoltage mechanism for assessing the frangibility of a distribution network. The method comprises following steps: step 1. based on the equivalence principle, establishing equivalent parameter models for the rest circuits after a circuit i is removed from the distribution network and establishing a ferromagnetic resonance importance model T(i) for the ith circuit in the distribution network; establishing a ferromagnetic resonance importance model for the nth set voltage transformer in the distribution network; step 2. according to the circuit ferromagnetic resonance importance model and the ferromagnetic resonance importance model of the voltage transformer, calculating the ferromagnetic resonance overvoltage frangibility of the circuit i; step 3. calculating the ferromagnetic resonance overvoltage structural frangibility of the whole distribution network. The quantification of the ferromagnetic resonance overvoltage structural frangibility and the circuit ferromagnetic resonance overvoltage frangibility can effectively identify weak links and potential dangerous points in the process of activating distribution network resonance.