A novel combined pretreatment of deacetylation and liquid hot water (LHW) was invented which has been proved to be effective in increasing enzymatic hydrolysis yield of biomass. In order to further understand the effect of this new pretreatment process on biomass, the variation on structural properties including cellulose crystallinity index (CrI), specific surface area (SSA) and degree of polymerization (DP) before/after pretreatment and how these properties affected the enzymatic hydrolysis of biomass were explored. The improvement of pretreatment severity (PS) could increase CrI, SSA and reduce DP. Whereas the enhancement of degree of deacetylation could decrease SSA and DP. An optimal formula (E<SUB>12Y</SUB>=0.347(100-CrI)<SUP>-0.375</SUP>x(SSA)<SUP>0.203</SUP>x(1700-DP)<SUP>0.281</SUP>) was achieved to express the correlation between structural properties and enzymatic hydrolysis after 12h. The enzymatic yield was more sensitive to CrI than to SSA and DP.