Amino-sulfonic acid-based water-reducer is characterized by high water-reducing rate and restraining the concrete mixture from slump loss with time. The application of amino-sulfonic acid-based waterreducer in concrete mixture was restricted due to its high bleeding. Based on principles of molecular design, the traditional superplasticizer of aminosulfonic acid series was modified by the suitable functional group introduced by monomer A and monomer U. The effects of such product on the fluidity, fluidity loss with time and bleeding rate of cement paste were tested. It was found that the modifying effect of monomer A for the superplasticizer was better than that of monomer U. The dispensability and flow retainability of superplasticizer were strong and the bleeding rate of cement paste added with superplasticizer modified by 9% monomer A was reduced obviously.