Abstract: Reloading error took place at Dampierre nuclear power Station unit 4 in April 2001 in French,which lowered the sub-critical margin.Although “the snake” reloading process is adopted in nuclear power Station in Guangdong Province,it is still necessary to perform the safety analysis focused on the similar accident during the fuel reloading,in order to verify the safety of fuel reloading process in nuclear power Station in Guangdong province.Based on the conservative calculation considering the disadvantageous fuel cycle of Ling’ao and Daya Bay reactors,the results show that the similar reloading error will result in the arrangement of new fuel assemblies in one place,but the sub-criticality required by FSAR can be satisfied and safety can be guaranted.