In this paper, an excitation current identification method is proposed based on the time-domain field-circuit coupled model. The electromagnetic coupling state equation of transformer is established. Based on energy disturbance principle, two state variables of dynamic inductance and time-domain current are calculated, the identification method of transformer excitation current parameters is studied by port electrical information. The electromagnetic characteristics of transformer under AC/DC hybrid and inter turn short circuit are studied, and combined with saturation state of transformer, the changing rule of excitation current under different conditions is summarized. The experiment platform of 220V three-phase group transformer is established,under different DC disturbance and inter-turn short circuit with different voltage levels, the excitation current is identified by excitation parameter identification module. And the simulation results are compared with the experimental data,the correctness of the simulation model is verified.