Abstract: To satisfy the requirements on thermal stability and adhesion in textile sizing,a new polyacrylic acid was prepared by emulsion polymerization using acrylic acid,acrylamide,methyl methacrylate,ethyl acrylate and butyl acrylate as monomer,12-alkyl sodium sulfate(SDS) and OP-10 as complex emulsifier and ammonium persulfate(APS) as initiator.Effects of dosage of the initiator and emulsifier,reaction temperature,time and stirring velocity on viscosity and adhesion of the size were discussed.The results indicate that the best process conditions of preparation are dosage of the initiator and emulsifier of 3% and 0.9% respectively,at 80 ℃ for 3 h,and stirring velocity of 140 r/min.