Copolymerization of Maleie Anhydride(MA) with sodium acrylate(AANa) initiated by plasma in aqueous solution was studied.MA-co-AANa was obtained and proved by IR.The experimental conditions were optimized,i.e.,discharge time was 70 s,discharge power was 80 W,post-polymerization time was 1 h,monomer ratio m(MA) : m(AANa) = 30:70 and post-polymerization temperature was 90℃.The conversion of monomer could reach to 32% and the sequestration of MA-co-AANa could reach 340 mg CaCO₃/g under these conditions.