Abstract: t Aim ：To prepare novel aqueous polymer dispersions with high flexibility for sustained-release coating and investigate their properties. Methods ：The aqueous polymer dispersions were synthesized by the emulsion polymerization.The physico-chemical properties and film-forming potential of the dispersions were investigated while the mechanical properties of the formed film and the drug release behavior when atenolol pellets were coated with the aqueous polymer dispersions were evaluated. Results ：The prepared aqueous polymer dispersions (methyl methacrylate/ethyl acrylate，1∶2 ) were found to have proper physico-chemical properties，excellent film-forming capability and satisfying mechanical properties.It could form free film with high flexibility and low viscosity in low temperature even in absence of the plasticizer.Sustained release of atenolol pellets was achieved when the pellets were coated the polymer dispersions.4-h and 8-h cumulative releases were more than 50% and 80%，respectively.There was no significant difference in release between pellets prior to and post compression of the coated pellets. Conclusion ：The resulting aqueous polymer dispersions could be used as sustained-release coating material with high flexibility suitable for tableting.