A novel separation mode was advanced for the study on the continuous moving chelation boundary (MCB) formed with EDTA and two metal ions, Co(Ⅱ) and Cu(Ⅱ).Experiments to elaborate the mechanisms of separation indicated that: (1) there are three boundaries in the whole system, a vertical MCB, a wide moving substitution boundary (MSB) and a sharp complex boundary (CB); (2) within the MSB, an ion substitution reaction occurs between [Co-EDTA]2 and Cu(Ⅱ); (3)because of the novel separation mode induced by the MSB as well as the merging of the MCB and CB,the original low concentration Co(Ⅱ) and Cu(Ⅱ) are chemically separated as two characteristic colored zones of pink [Co-EDTA]2 and blue [Cu-EDTA]2-, and the sensitivities for detection of the two metal ions are greatly enhanced.