Abstract: Because of the nonlinearity of arc, numerous high-order harmonics will come to occur in the arc furnace operational process and can result in voltage fluctuations and flicker in the power network. To solve the above adverse problems, a new time domain arc model for arc furnace is developed, which is based on the physical mechanism of arc and takes the arc conductance as the state variable to express the model in terms of a nonlinear differential equation. In addition, the method to calculate the model parameters is given. The arc model can fully account for changes in the different parameters of the electrical power system by adjusting arc model parameters. The simulation results showed that the output arc voltage/current calculated from the model is basically in conformity with the voltage/current measured in situ, thus verifying the validity of the new arc model.