With the development of technology nodes below 5 nm, cobalt has attracted extensive attention as an interconnection metal to replace Cu in the next generation of interconnection technology. Here, the appropriate concentrations of colloidal silica, H 2 O 2 , and BTA in the polishing solution were determined by static electrochemical measurement and electrochemical mechanical polishing technique. The results showed that the dynamic material removal rate of cobalt could be greatly improved after the addition of the selected solution. X-ray photoelectron spectroscopy was used to explore the reaction process and material generation in the polishing process. Co(Ⅱ)-BTA complex was found to be generated in the reaction process and adsorbed on the surface of cobalt, and it could be removed under a small mechanical force. Finally, the surface roughness of Co under different polishing time was measured by atomic force microscopy. The roughness of cobalt surface was Ra 1.35 nm polished for 10 min, and Ra was 0.418 nm after polishing for 120 min.