The low yield of fermentable sugar of hydrolysis of cellulose is the bottle-neck problem in conversion of cellulose-ethanol. The aim of this paper is to improve the yield of hydrolysis by the crystal structural change of cellulose based on chemical modification. A new 1,3,5-triazine derivative 2-chloro-4,6-dianilino-1,3,5-triazine (DACT) was synthesized from 2,4,6-trichloro-1,3,5-triazine (TCT) and aniline. The structure of DACT was characterized by IR and ¹H NMR spectra. Microcrystalline cellulose (MCC) was chemically modified with DACT and the modified MCC were hydrolyzed to study the impact of the amount of DACT on the crystal structure and the hydrolysis property of cellulose. The hydrolytic conditions were as follows: the concentration of sulfur acid was 70%, the solid to liquid ratio was 1∶10 (W/V), the temperature was 50 ℃ and the hydrolysis time was 60 min. The result showed that when the relative molar percentage of DACT (by the cellulosic glucose ring) was about 30%, the yield of the reducing sugar was the highest. The WAXD spectra confirmed that this result was due to the change of the crystalline structure of cellulose by chemical modification, which was beneficial for the hydrolysis of cellulose.