Abstract: Based on the expression of electrode regulator system as a time-variant N-L-N model, an online method is proposed to identify the electrode regulator system of electric arc furnace, which improves the model precision as time-varying of arc characteristic. To deal with the difficulty on parameter separation during the process of on-line identification, the idea that updating parameters of linear and nonlinear parts respectively is derived. Simulation results validate the effectiveness of the proposed algorithm on tracking the parameters of the model which achieves the purpose of monitoring system parameters real-time.