Simulation system of substation was built through electromagnetic transient software ATP-EMTP. Based on simulating specific circumstances of 110kV into line, the lightning arresters were installed on main transformer of a coal mine substation which were not in the same position, the high and low voltage side with the bus under the lightning overvoltage amplitude and duration were made simulation calculation. Optimal installation principles were put forward through these results, which could minimize the overvoltage magnitude at time of transformers suffering intruding wave in substation