Abstract: Before core fuel loading design for nuclear power plant refueling outage, subject to the enrichment of core fuel assemblies, reactivity control, operation time and other factors, partial fuel assemblies suffer from irradiation deformation and meet difficulty during loading. It is necessary to alter loading sequence to place all fuel assemblies into reactor core. At present, the alteration of core loading sequence is manually realized by Office software, which requires manual marking for new fuel assemblies and manual calculation & verification for adjusted loading sequence, resulting in heavy workload and high human?error risk. This paper presents a developed PWR fuel assembly loading-sequence altering system. The system can automatically identify fuel assemblies with loading risks and output optimized reasonable loading sequence.