Cellulose, as the primary structural component of plant cell walls, plays a crucial role in maintaining plant morphology and supporting growth processes. It is recognized as the natural polymer material with the highest modulus in nature. Owing to its renewability, multi-scale structural hierarchy, and exceptional mechanical properties, cellulose has become a widely utilized natural material. Since microstructure determines macroscopic properties, understanding the origin of its remarkable mechanical strength requires fundamental investigation starting from cellulose molecular structure. Analyzing how its multi-scale architecture influences mechanical performance is key to comprehending its high modulus characteristics. Experimental and simulation studies have demonstrated that its Young”s modulus ranges between 100-200 GPa. However, the specific contribution ratios of intermolecular versus intramolecular hydrogen bonds to its mechanical properties remain unclear, and the relative mechanisms of different hydrogen bond types and dispersion forces in mechanical performance remain controversial. This study systematically investigates the influence mechanisms of intermolecular hydrogen bonds (O3H…O6), intramolecular hydrogen bonds (O2H…O6, O3H…O5), and dispersion forces on cellulose”s mechanical properties through density functional theory (DFT) calculations. By comparing the tensile moduli and elastic tensors of cellulose Iβ structures with/without dispersion corrections and fluorine cellulose structures, we elucidate the respective roles of these interactions.