The experimental study on the fault using the original model of a large transformer is of long period and high cost, and it is not easy to obtain valid data.It is convenient to obtain more comprehensive fault data through simulation, which is helpful to the study of diagnosis method.The parameters of the transformer winding distribution parameter model under lightning impulse voltage are not comprehensive and have a certain error, which is unfavorable for the fault feature analysis.A single phase two-winding transformer model was taken as an example.The winding distribution parameters were calculated by the finite element method.Through the comparison with the multi-conductor transmission line model, the reasonable electrical parameters were selected to establish the improved distributed parameter model.The simulation results show that the model can be used to more accurately simulate the fault of transformer windings under lightning impulse, which is conducive to research on fault feature analysis and diagnosis method.