Abstract: To develop green, biodegradable filter materials with antibacterial properties, Lyocell fibers and hemp fibers were bonded via hydroentanglement, exploiting the fibrillation characteristics of Lyocell and the surface microfibrillation of hemp. An experimental study was designed to investigate the effects of different water jet energy levels on the fiber splitting degree, filtration efficiency, and pore structure of the two fibers and their composite. FT-IR analysis was employed to examine the bonding mode between a composite ammonium salt antibacterial agent and the cellulose fibers, and the changes in antibacterial performance, filtration efficiency, and mean pore size after antibacterial finishing and damp-heat aging were evaluated. The results showed that with the accumulation of water jet energy, the splitting degree of both fibers intensified, the air permeability of the hydroentangled material decreased, the maximum filtration efficiency reached 79%, and the pore size shifted. After antibacterial finishing and damp-heat aging, the antibacterial activity gradually decreased from 100% to 97%, the PM_2.5 filtration efficiency dropped from 79.5% to a minimum of 69.1%, and the mean pore size increased from 23.41  μm to 30.39  μm. Analysis indicated that increasing the water jet energy significantly enhanced the splitting of the Lyocell-hemp composite, reduced the pore size, and improved the filtration efficiency. The antibacterial macromolecules were bound to the fibers through intermolecular forces. After damp-heat treatment, the antibacterial performance of the material declined, the structural integrity of the microfibril membrane decreased, and localized cracks or defects appeared.