A novel amphoteric polycarboxylic (APC) acid-based superplasticizer was prepared by solution copolymerization from maleic anhydride, allyl polyethylene glycol, and methacryloxyethyltrimethyl ammonium chloride (DMC). The cationic monomer DMC was introduced for improving the performances of sulfoaluminate cement (SAC) with APC. The condition on preparation of APC was determined by the orthogonal experiment, and the performances of fresh and hardened superplasticized mortars were assessed. APC was characterized by FTIR spectra. Adsorption amount and dispersing effectiveness of APC were also investigated. Results indicated that APC could improve the fluidity and enhance the mechanical performances of SAC mortars. Adsorption amount of APC in SAC is large. Compared with an anionic PC superplasticizer and a commercial superplasticizer Visco Crete 3390, APC has the better performance. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012