With the increasing level of voltage in electric networks，the allowable value of switching over-voltage of the transmission lines has become more and more concerned matter. The method， in which arrester and closing resistor are applied to limit switching over-voltage， is extensively used in EHV. With ATP-EMTP， hence， the effects for the arrester and closing resistor to limit over-voltage in synchronizing switching of UHV system are investigated on the first 1 000 kV UHV AC transmission pilot project in China. The transmission system lies from the southeast Shanxi， via Nanyang in Henan province， to Jingmen in Hubei province. The results of simulations in this paper indicate that the strategy to use multi-stage closing resistors or use MOA in both the ends and mid of the line can work well for limiting the over-voltage of 1 000 kV UHV AC transmission system.