The invention discloses polylactate polyamide ultrafine composite fiber. The polylactate polyamide ultrafine composite fiber comprises the following components in parts by weight: 50-60 parts of ultrafine polyamide, 40-50 parts of polylactic acid fiber, ultrafine polyamide is taken as a core wire, the core wire is coated with polylactic acid fiber; the ultrafine polyamide comprises 85-95 parts of chinlon-6 chips, 5-7 parts of active carbon and 6-10 parts of nano silica; polylactic acid fiber comprises 100 parts of polylactic acid, 5-10 parts of a maleic anhydride grafting compatilizer, 1-2 parts of tert-butyl peroxybenzoate, 5-8 parts of citric acid, 10-16 parts of tert-butyl alcohol, 2-6 parts of zinc oxide, 2-5 parts of vinyl polydimethyl silane, and 0.2-0.5 parts of phosphate. The prepared composite fiber has the characteristics of comfortable hand feeling, good elasticity, degradable performance, egradable performance, and certain antibacterial property, by tight coating of core wire and polylactic acid fiber, the composite fiber has the advantages of high intensity and difficult fracture, and a preparation method is simple and feasible.