Mechanical fragmentation is an important pretreatment in the biomass biotransformation process. Mechanical fragmentation at the tissue scale significantly reduced the particle size of rice straw but did not significantly change its crystalline properties; the increase in the glucose yield was limited from 28.75% (95.55 mg/g substrate) to 35.29% (115.28 mg/g substrate). Mechanical fragmentation at the cellular scale destroyed the cell wall structure and reduced its crystalline properties. Thus, the glucose yield also showed a significant increase from 35.29% (115.28 mg/g substrate) to 81.71% (287.07 mg/g of substrate). The quantitative equations among the particle size, crystalline properties and glucose yield (mg/g substrate) are as follows: CrI = 44.14 x [1 exp(0.03658 x D-50)] and CP = (8.403 x logD(50) 24.18 36)/(1-4.225/D-50<^>0.5); GY = -5.636CrI + 343.7 and GY = -14.62CP + 512.1; and GY = 97.218 + 247.5 x exp(-0.03824 x D-50). The quantitative correlations among the mechanical fragmentation scales and crystalline properties can determine the effect and mechanism of mechanical fragmentation on biomass and can further promote the construction of a cost-competitive biotransformation process for biomass. (C) 2017 Published by Elsevier Ltd.