The invention provides a method for preparing a chitosan/rare-earth composite antibacterial fiber, and relates to the technical field of functional fiber production. According to the method, two materials, namely chitosan and rare-earth, are mixed with PVA for electrostatic spinning, wherein the chitosan has a good adsorption effect on multiple harmful substances in water, the rare-earth can react with hydroxyl, amidogen and other active radicals in chitosan molecules, a product can be used for overcoming the defect of single phases of the chitosan, the rare-earth and the PVA and has the advantages of thermal stability of inorganic materials and polyfunctionality of organic materials, so that the chitosan/rare-earth composite antibacterial material can be used for breaking through the defect of the single chitosan on performances, and reducing the use amount of the chitosan, so that the using cost can be reduced while the antibacterial performance is improved.