In multiwinding transformers, different geometry of the individual windings leads to unbalanced leakage flux paths. The unbalance affects the behavior of the power electronic converters, where these transformers are used. This paper proposes an approach to model the leakage flux path of transformer with repetitive multiwinding structure using permeance magnetic circuit. The model is composed of lumped components, it can be seamlessly integrated into system-level simulation of power electronic circuits and achieve good accuracy in time-domain simulation. Taking advantage of the repetitive structure, the model requires very limited number of parameters, which can be easily obtained from the geometry information together with only a few experimental tests. The fidelity of the model is experimentally confirmed on a multiwinding transformer prototype connected to power electronic devices.