This paper investigates the additional iron loss generated in the laminated silicon sheets of the core or the magnetic shields of large power transformers due to the leakage flux. A verification model is well established, and an efficient analysis method is implemented and validated. Both the magnetic and electric anisotropy of the oriented silicon steel sheets are taken into account in 3-D FEM eddy current analysis. The calculated and measured results with respect to the test model are in good agreement.