The present invention discloses a polylactic acid nanometer complex concurrently having toughness and strength, and a preparation method thereof, and belongs to the field of polymer materials, wherein the complex comprises a polylactic acid matrix resin, a toughening agent and a reinforcing agent. The preparation method comprises: adding natural latex and deionized water to a reactor, and adding potassium hydroxide and sodium lauryl sulfate; introducing protective gas, adding isopropyl alcohol, uniformly mixing, adding glycidyl methacrylate, heating, and adding an initiator and a catalyst; carrying out a reaction, drying, carrying out immersion washing, drying, extracting, and drying to obtain NR-g-GMA; adding polyethylene glycol, elemental sodium wire and toluene to the reactor, carrying out a reflux reaction, cooling, adding epibromohydrin, carrying out a reaction, filtering, adding the filtrate to ether, precipitating, washing, and drying to obtain PEG-EP; adding a NaOH solution to a cellulose nano-crystal aqueous solution, uniformly mixing, adding the PEG-EP, carrying out a reaction, carrying out dialysis, and drying to obtain CNC-g-PEG; and carrying out melt blending on the dried polylactic acid matrix resin, the NR-g-GMA and the CNC-g-PEG so as to obtain the complex.