Abstract: Nano-cellulose was prepared by the hydrolysis of the alkali pretreated reed pulp with 55% (by mass fraction) sulfuric acid. The effects of reaction time, reaction temperature and alkali treatment time on yield and the mean size of nano-cellulose were studied. The optimizing preparation condition for single factor test is 1.0 h of alkali treatment time, 60 ℃ of reaction temperature and 2.0 h of reaction time. Under this condition, the yield of nano-cellulose is 54.50% and its mean size is 156.9 nm. The analysis of fourier transform infrared(FT-IR) and X-ray diffraction(XRD) showed that nano-cellulose from reed pulp pretreated by alkali is cellulose typeⅡ. The orthogonal test was investigated based on single factor test. The results showed that the technological parameters optimized by conducting orthogonal test for the yield of nano-cellulose are 1.0 h of alkali treatment time, 60 ℃ of reaction temperature and 3.0 h of reaction time. The highest yield of nano-cellulose (55.64%) with 166.3 nm mean size was achieved.