Abstract: Dispersant for paper filling was synthesized.Effects of acrylic acid/maleic anhydride ratio and type of initiating agent on rasin viscosity and dispersion were discussed.Dispersant from acrylic acid/maleic anhydride molar ratio 1.5 can well disperse calcium carbonate paste,while polyacryllic acid disperses calcium carbonate paste best.Ammonium persulfate ferrous sulfite sodium bisulfite is the best initiating agent.Sodium bisulfite is 13.5% and ferrous sulfite is 0.006 7% of monomer.Optimal conditions were determined.