One kind of branched Poly(vinyl alcohol) has been synthesized via common radical copolymerization of vinyl acetate in methanol by adding a bifunctional monomer Allyl methacrylate (AMA) followed by saponification. The comonomer AMA has two reactive double bonds that can provide the branching points to macromolecule chain structure. With these reactive points, the copolymer with long chain branches can be obtained. The long chain branches bring the copolymer higher viscosity by the entanglement of them between macromolecules and strong hydrogen bonding between long chain branches. The viscosity of the water solutions increased with the amount of the comonomers' addition increased. The branched PVA has good water maintenance properties at relatively high temperature. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4608-4612, 2013