Lignosulfonate is an anionic polymer surfactant and can be used as concrete water reducing agent, but it makes common effects only. The work aims to improve using effects of lignosulfonate water reducing agent by modifying it by taking advantage of graft copolymerization-sulfonation reaction. Effets of graft copolymerization, sulfonation reaction order as well as the dosage of graft monomer and suffocating agent on actual using effects of lignosulfonate water reducing agent were studied in the aspects of water-reducing rate, setting time and compressive strength by performing two modification reactions simultaneously. The reaction order was determined, optimal dosage of crylic acid and sodium sulfite as 10% and 30% of lignosulfonate dosage repectively was obtained. All properties of the concrete were improved. For concrete mixed with unmodified lignosulfonate, the compressive strength reduced significantly. For concrete mixed with modified lignosulfonate, the compressive strength increased to a certain extent. Graft copolymerization and sulfonation reaction modification can enhance the using effects of lignosulfonate water reducing agent and improve various properties of concrete significantly.