In order to study the effect of environmentally friendly additive chito-oligosaccharide(COS) on the chemical mechanical polishing process of 304 stainless steel,and to explore its interaction and adsorption mechanism with metal surface during the polishing process,the influence of COS organic molecules on chemical mechanical polishing of 304 stainless steel was studied using methods such as chemical mechanical polishing experiments,contact angle measurements,scanning electron microscopy (SEM) and energy dispersive spectrometer(EDS) analysis.The global reaction parameters of COS molecules were studied by quantum chemical calculation,the reaction active sites were analyzed and calculated,the adsorption of organic molecules on metal surface was simulated by molecular dynamics,and the radial distribution of active atoms was analyzed.The results show that the incorporation of COS in the chemical mechanical polishing (CMP) process leads to the formation of a hydrophobic film on the surface of 304 stainless steel via adsorption mechanisms.This film effectively hinders the etching action of oxidizing agents on the stainless steel surface,thereby enhancing the resulting surface quality after the polishing treatment.The best surface quality with surface roughness of 1.65 nm is obtained when the mass concentration of COS is 400 mg/L.Quantum chemistry studies show that the active reaction sites of COS are mainly O atoms,which can form multicentric adsorption on metal surfaces.Molecular dynamics simulations show that COS organic molecules can be adsorbed on metal surfaces in parallel,and O atoms in organic molecules can form coordination bonds with iron atoms,which dominates adsorption.