As a hygroscopic polymer, acrylic water-soluble polymers were prepdred by suspension polymerization and were saponified with aqueous NaOH and purified by washing with methanol to remove 411 traces of excess NaOH. The compositions of Poly(MA-co-VAc) wIns verified by elemental analysis, IR, NMR spectroscopy and Poly (MA-co-VAc-co-MMA) was by IR and NMR spectroscopy. Hygroscopic capacity of these polymers was measured on aqueous NaOH solution and increased with the order of Poly (MA-co-VAc-co-MMA) < Poly sodium acrylate < Poly (MA-co-VAc). In these cases, hygroscopic value of Poly (MA-co-VAc) was 540 g/g. In the case of Poly (MA-co-VAc), hygroscopic capacity was increased with the increase of water content in the aqueous solution of nonelectrolytes and decreased with the increase of ion concentration in that of electrolytes. While the swelling remained constantly high in the pH range of 5-9, it dropped drastically when pH was lowered further. Hygroscopic capacity of polymer was not affected largely with the variance of temperature, find decreased with the increase of drying temperature.