The invention discloses a power transmission line fault propagation model, which is a framework structure model based on asymmetric inertia distribution. Generator nodes are set to be vertexes, and lines are set to be branches, so that a topological structure of a power grid is equivalent to a framework structure and comprises transmission paths between a generator bus and a generator bus. By selecting generator power angle increment and unbalanced power increment as key factors for analyzing disturbance propagation, and a giving a transfer matrix in uniform dielectric power grid lines, the model can represent state parameters of the power grid under disturbance in real time, and can analyze the transfer process of disturbance in an actual power system.