A novel stationary phase for strong cation exchange chromatography was prepared by “grafting from” strategy.Atom transfer radical polymerization(ATRP) of sodium 4 vinylbenzenesulfonate(NaSS) was conducted in N,N dimethylformamide(DMF) solution at room temperature,which was synthesized by the chemical modification of 7 μm monodisperse PGMA/EDMA beads as initiator,CuCl/CuCl2/Bpy as catalyst system,under a nitrogen atmosphere with a closed system.The amounts of NaSS grafted chains with different ATRP formulations were calculated based on the elemental analysis.The effects of the NaSS grafted chain lengths on PGMA/EDMA beads for the separation of proteins,adsorption capacity,pH of mobile phase on the protein retention were investigated in details.Under the condition of catalyst∶ligand∶monomer with mole ratio of 1∶5∶100,the dynamic capacity of this packings was obtained to be 465 mg/gThe results showed that four proteins were completely separated in 10 min by linear gradient at a flow rate of 10 mL/min,and the retention time of packing increased with the increase of monomer，which was found to follow the cation exchange chromatographic(IEC) retention mechanism.