Abstract: Abstract: Multiple sustainable energies have been expected to replace the fossil feedstock-driven system in recent years. Among them, biomass from plants, animals, and microorganisms has been accepted as one of the most abundant and renewable carbon-based materials worldwide. Since the sugar beet (Beta vulgaris) as an important sugar crop has been widely cultivated in the world, a large amount of residue can be generated during the planting and processing of sugar beet, which is regarded as the significant raw feedstock in biomass conversion and biorefinery. Furthermore, different organs or tissues exhibit remarkable heterogeneity in the chemical components, physical properties, and cell morphologies. Particularly, there are the complex and ambiguous effects of heterogeneity on enzymatic hydrolysis. It is also a high demand to clarify the resistance in organs and tissues for the high-value utilization of sugar beet. In this research, a systematic investigation was conducted to determine the influences of physical-chemical properties on the sugar yield of sugar beets. Specifically, the chemical components included the neutral detergent soluble, cellulose, hemicellulose, and lignin, whereas, the physical structures included the degree of polymerization, crystallinity, and specific surface area of cellulose. Furthermore, a Confocal Laser Scanning (CLS) and fluorescence microscope were utilized to characterize the adsorption of cellulase on the cell wall and the morphology variation during enzymatic hydrolysis, respectively. The results showed that the root of sugar beets contained much more neutral detergent soluble, yet less cellulose, hemicellulose, and lignin. There were similar physical properties of cellulose in the root and stem of sugar beets, but significantly different from that in the leaf. The cellulose in the leaf and stem presented a higher crystallinity index and specific surface area, but a lower polymerization degree, compared with the root. Correspondingly, the different reducing sugar yield was observed in the root, stem, and leaf of the sugar beets. Specifically, there were similar reducing sugar yields of root (14.64%) and stem (14.26%), which were around 1.40-1.44 times higher than that of the leaf (10.15%). The correlation analysis demonstrated that the lignin was significantly and negatively correlated to the reducing sugar yield (P<0.01). Moreover, the reducing sugar yield was significantly and negatively correlated with the hemicellulose (P<0.01), yet with the specific surface area significantly and positively (P<0.01). However, there was no significant correlation between the reducing sugar yields and the rest of the physicochemical characteristics. Overall, the cellulase adsorption and enzymatic hydrolysis of roots and stems were superior to the leaves. Microscopic observation showed that the parenchyma cells in the root behaved with a strong adsorption capacity for the cellulose much easier to be degraded. This finding was consistent with the trend of reducing sugar yield. Although the cellulase performed a high-affinity binding with the xylem of vascular tissue in the stem, there was a relatively low enzymatic digestion caused by the nonspecific adsorption of lignin. There were also relatively low adsorption and enzymatic digestion of other tissues and cells. The lignin, hemicellulose, and specific surface area were the important factors to dominate the efficiency of enzymatic hydrolysis. In general, the thinner and less dense cell walls were degraded rapidly and completely. Localized morphological analysis showed that the mixed cellulase firstly degraded the middle lamella, and then fragmented and separated the cell walls into disorganized segments. The disorganized cell walls further increased gradually to shear and break over the hydrolysis time. Additionally, the remained regions of the cell wall after the enzymatic hydrolysis were recognized as the cell wall corner. The compiled data revealed that the highly complicated physical-chemical properties of the cell wall interface greatly contributed to the cellulase adsorption and saccharification. The findings can provide a strong reference for the energy crop of sugar beets.