Modified lignin cement water-reducer was prepared via hydroxymethylation followed sulfonation of wheat straw ethanol lignin. The optimum process conditions of sulfonation of wheat straw ethanol lignin were mainly investigated. Fourier transform infrared spectroscopy (FT-IR) was performed to characterize the chemical structure of mofified ethanol lignin. Its morphology was revealed by the scanning electron microscopy (SEM) observation. The application results showed that when the modified lignin dosage was 0.5% the fluidity of cement paste reached 208mm, water-reducing ratio was 14.9% which was 30.7% higher than using commercial Sodium Lignosulfonate; and with the addition of modified ethanol lignin, the 3 and 7 d compressive strengths of concrete are13.8 % and 9.9 % higher than using commercial Sodium Lignosulfonate respectively.