Abstract: This report introduced a new simple method for preparing purified monoclonal antibodies （McAb）,which could be called as the anion and cation exchange chromatography.For the molecules of monoclonal antibodies were uniform in charge,so the chromatography column that contains anion resin and cation resin was produced.In this condition,the McAb which is in facultative ion state can flow fast in column,and the other proteins whose isoelectric point is not equal to the McAb’s take positive charge or negative charge and can be absorbed by the resin among the chromatography column,so these proteins flow slower in the column.As the result, the McAb can be separated from ascites fluid.We purified 3B₃ McAb against human colon carcinoma by this method.The purity of 3B₃ McAb is more than 90%.