The accurate simulation calculation of overvoltage of arrester for AC filter is the basis of its insulation design and stable operation. In this paper, the modeling and simulation calculation under the condition of filter input and AC bus grounding fault are carried out by using the modeling method of gradually refining model. The effects of stray parameters of AC filter, π-type equivalent circuit of lines inside and outside the AC filter field and protection strategy of AC filter on the overvoltage simulation results of lightning arrester used in AC filter are analyzed. The simulation results show that under the above operating conditions, after considering the three parameters, the overvoltage of the arrester changes -4%~25%, the current decreases 36.2%~62%, and the absorbed energy increases 16%~214%. Therefore, if the above factors are not considered in the insulation design, the voltage and current design value of the lightning arrester will have a large deviation, and the energy design value will be small, which will affect the normal operation of the AC filter.