The synthesis of urethane acrylate anionomer introducing the unsaturated ionic group was performed via stepwise procedure, using hydroxy-terminated poly(oxytramethlene)glycol (PTMG) as a soft segment, isophorone diisocyanate (IPDI), THPP-TPA, and 2-hydroxyethylacrylate (2-HEA). THPP-TPA incorporated into the molecular backbone acted as a hydrophilic group, leading to obtain the water-soluble prepolymer. THPP-TPA was synthesized from the esterification of 1,2,3,-tri(2-hydroxypropoxy)propane(THPP) with tetrahydrophthalic anhydride(TPA). Characterization of urethane acrylate anionomer introducing the new ionic gruop was carried out by Differrential Scanning Calorimetry (DSC), Dynamic Light Scattering (DLS), Universal Testing Mechine (UTM).