Both alkaline organosolv and formaldehyde stabilization pretreatment can yield high-quality lignin by preventing condensation. For the hydrogenolysis of the pretreated solid residues, the highest yield of C2-C4 chemicals was 66.8% under alkaline organosolv pretreatment for 60 min. Specifically, the crimped fibers and residual lignin and hemicellulose increased the surface roughness of the residue by 40.6%, the crystallinity index decreased to 44.4%, and the crystal size was reduced to 2.15 nm, which in turn promoted hydrogenolysis of the residue. However, the increase of crystallinity and crystal size and the decrease in surface roughness of the formaldehyde stabilization pretreatment residue greatly hindered the conversion of polysaccharides. In addition, residual formaldehyde on the residue may also inhibit catalyst activity. Overall, this study provides novel perspectives on the full utilization of biomass, as well as new insights into the conversion of polysaccharides.