The invention provides a polylactic acid tow for cigarettes, which is made of the following raw materials in parts by weight: L-lactide, stannous octoate, polyene thermoplastic PP masterbatch, food-grade silica gel masterbatch, oligomeric lactic acid-β-ring Dextrin, food grade sodium carbonate, polyethylene glycol oleate, hydroxymethylcellulose, deionized water. The present invention also provides a preparation method of polylactic acid tobacco tow, including rinsing, drying, direct melting, melt extrusion, polymerization, extrusion devolatilization, melting, mixing, microwave treatment, spinning, cooling, Winding, drawing, curling, drying. The invention also provides the application of making the polylactic acid tobacco tow into a cigarette filter. The invention has beneficial effects: the cigarette filter tip has moderate suction resistance range, good adsorption effect on harmful substances in smoke, good deformation resilience, moderate ventilation rate, good thermal shrinkage performance and good physical properties.