Objective To optimize the condition for removal of acidic variants in purification process of monoclonal antibody(McAb)against human epidermal growth factor receptor 2(HER2). Methods The influences of elution method, p H value and salt concentration of buffer for pre-elution, pre-elution volume, antibody loading in filler on removal of acidic variants were investigated, based on which the process for removal was optimized and verified for suitability in four batches of recombinant McAb against HER2 in pilot scale. Results The optimal process was as follows:the antibody loading in filler was not less than 60 g/L. After sample loading/leaching, 20 mmol/L Tris-HCl at a pH value of 8. 0 and15 mmol/L sodium chloride at a conductivity of 3. 0 mS/cm were added, and the column was pre-eluted by the preelution buffer in a 3 times of column volume, then equilibrated with equilibrium buffer in 5 times of column volume and eluted. By the optimal process, the content of target component increased from 53% to 65%, while that of acidic variants decreased from 35% to less than 25%. The charge distribution was consistent with that of control. Of the four batches of samples for pilot verification, three batches at antibody loadings of not less than 60 g/L met the relevant requirements for the control. Conclusion The optimized process of cation exchange chromatog. for removal of acidic variants was simple, effective and easy to handle, which was suitable for pilot production