Abstract: AFA 2G assemblies in Ling’ao nuclear power station were replaced gradually by AFA 3G assemblies from cycle 2 and subsequent cycles.The enrichment of the fuels was increased from 3.2% to 3.7% from cycle 3 in Ling’ao.Therefore,the study of Ling’ao mixed core and increased enrichment was launched in 2001.Rod drop accident for Ling’ao Nuclear Power Station was reanalyzed in the frame of Framatome ANP analytical methodology.The analytical codes used in the accident analysis includes SCIENCE,ESPADON,CINEMA,CANTAL and FLICA III.For detected dropped rod configurations,the negative flux rate protection system actuates a reactor trip.For the non-detected dropped rod configurations,the minimum DNBR values have been evaluated with the conservative analysis methodology and assumptions,and the DNBR fuel design limit is respected.