The performances of CSAX in wastewater treatment were evaluated by flocculation experiment. The results show that the CSAX was successfully synthesized and it has functions of removing both turbidity and copper ions from aqueous solution. It was proved that CSAX is more effective than crosslinked starch xanthate (CSX) and much more effective than crosslinked starch-graft-polyacrylamide (CSA) for removing copper ions. It was also proved that CSAX is little less effective than CSA, but much more effective than CSX for removing turbidity.