The present invention discloses a water-solubility copolymer with an amantadine-containing pendant group and a preparation method thereof, the copolymer is a crylic acid-N-vinyl-pyrrolidone linear copolymer with an amantadine-containing pendant group, the amantadine is coupled on a copolymer pendant group-COOH through -COOH NH2-key, the unit structure is that the preparation method uses the crylicacid, crylic acid, the n-vinyl-pyrrolidone and the amantadine as raw materials, uses a low carbon alcohol as a dissolvent, uses the azobisisobutyronitrile as an evocating agent, and includes steps ofcrylic acid preprocessing, a solution polymerization reaction, precipitation, filtrating, laundering and vacuum drying; the water-solubility copolymer of the invention has superior characteristics ofa well water-solubility, a biocompatibility, an antiviral property and the like, and has latent purposes in fields of the medical sanitation, the pharmacy engineering, the biological engineering andthe like.