Short-circuit impedance calculation plays an important role in transformer designing. However for the special transformer with zigzag connection winding, concerning the particularity of winding arrangement and connection, the traditional engineering calculation method is not accurate enough. In this paper, the field circuit coupled method is proposed to the calculation of short circuit impedance of zigzag winding. Then, an export 220 kV power transformer with low voltage zigzag connection is taken as example, the short-circuit impedance is calculated by analytical formula and numerical simulation energy method respectively. Compared with the experimental results,it is verified that the numerical simulation calculation energy method that based on field coupling method has higher accuracy,and provides an effective reference for the impedance calculation of the same type transformer design.