The AC arc furnace is a typical pollution source of harmonic wave as well as a flicker source. It also produces larger inter-harmonic component during working near secondary harmonic. This paper analyzes and simulates the harmonic quantity and the parameters of SVC device of the arc furnace in a steel company. The conclusion shows that it is better to install the secondary filter of type C for the arc furnace in order to limit the harmonic and interharmonic near secondary. A new checking method is put forward for the secondary filter branch, which is a good method that can instruct the design of the AC arc furnace filter.