The interaction of host-guest molecules has attracted wide attention in analytical chemistry, molecular recognition and separative science as well as supra-molecule chemistry.In this paper, a novel model of moving interaction boundary (MIB) was developed which was created with a guest compound and a host molecule of cyclodextrin (CD) in capillary electrophoresis (CE).With norfloxacin (Nor) as the model compound, the relevant experiments were further carried out and further compared with those in capillary zone electrophoresis (CZE).