Using 4-((3,4-dihydroxyphenyl)diazenyl)benzenesulfonic acid and 4,4′-diphenyl- methane diisocyanate (MDI) as raw materials, the hyperbranched azo polyurethane was synthesized by A2+B3 polycondensation, with the reactions between phenolic hydroxy or sulfo group and isocyanate group. Then the peripheral hydroxyls of synthetic hyperbranched azo polyurethane reacted with succinic anhydride or trimellitic anhydride to to improve the polymer solubility. The target hyperbranched azo polyurethanes were characterized by IR, TG and UV-Vis spectrum. The UV-Vis spectra showed that both of the maximum absorption peaks of π→π* in the unmodified hyperbranched azo polyurethane and the hyperbranched azo polyurethane modified by trimellitic anhydride were the same, at 425 nm, while the maximum absorption peak of π→π* in hyperbranched azo polyurethane modified by succinic anhydride was red shifted to 501 nm.