Abstract: In the context of the “dual carbon” goals, biomass has attracted significant attention due to its advantages of low pollution and low carbon emissions. The hot-processing densification technology has been employed to enhance the mechanical properties and energy density of the molded biomass pellets to overcome the limitations of biomass, including low energy density and loose structure. The hot-processing densification experiments of the single, binary, and ternary biomass components (cellulose, hemicellulose, and lignin) were conducted and the mechanical properties of the resulted pellets were analyzed using an electronic universal material testing machine. Meanwhile, molecular dynamics simulations were performed to explore the microscopic evolutions and interaction mechanisms among the biomass components during the hot-processing densification process. The results show that the addition proportions of hemicellulose or lignin into cellulose can increase the compressive strength of the molded pellets up to the maximum value of 15.04 MPa with the mass ratio of cellulose to hemicellulose of 8∶2. The mechanical properties of the pellets made from the hemicellulose-lignin mixtures were low and the maximum strength of the hemicellulose-lignin mixture with the mass ratio of 5∶5 reaches only 2.89 MPa. In the binary blending simulation, the Mean Square Displacement (MSD) value was observed to increase as the densification degree increased. Coulombic electrostatic forces play a dominant role during the densification process and contribute to the increasing bonding performance of the molded pellets. However, as the densification degree increased to some degree, the repulsion caused by van der Waals forces became more pronounced. The cellulose-hemicellulose blending model exhibited the highest number and greatest increase in hydrogen bonds, while the cellulose-lignin blend showed fewer hydrogen bonds and a slower growth trend. The hemicellulose-lignin blend exhibited more fluctuating trend in the hydrogen bond count with less growth. For the ternary blend experiment, the optimal ratio of cellulose, hemicellulose, and lignin was determined as 7∶2∶1, with the best compressive strength of 16.02 MPa. The Radial Distribution Function (RDF) value, hydrogen bond quantity, van der Waals forces, and Coulombic electrostatic forces at the optimal ratio outperformed those of the C8 blend with the cellulose-hemicellulose-lignin mass ratio of 8∶1∶1. However, the high densification degree of the optimal blending ratio results in the increasing repulsive effect caused by van der Waals forces, which hinders further increase in the intermolecular forces.