The work aims to improve antibacterial properties of polylactic acid (PLA) film. Inspired by the fact that conductive polymer materials could exert antibacterial effect through electrostatic interaction, Fe3+ was applied to induce the chemical oxidation polymerization of pyrrole (Py) on the surface of PLA film to form antibacterial coating (PPy), so as to prepare PLA-PPy multilayer composite antibacterial film. Moreover, double antibacterial coating (PPy/Ag) was formed on the surface of PLA film by using the equivalent amount of Ag+ instead of Fe3+ to induce the polymerization of Py, and PLA-PPy/Ag multilayer composite antibacterial film was also successfully prepared. The effects of different oxidants and Py concentrations on the structure and properties of multilayer composite films were further investigated. When PLA film surface area, aqueous solution volume, FeCl3?6H2O concentration, and Py concentration were 72 cm2, 40 mL, 0.047 mol/L and 0.223 mol/L respectively, PPy layer of PLA-PPy multilayer composite antibacterial film was compact, but tensile strength (40.1 MPa) and elongation at break (24.9%) of PLA-PPy multilayer composite film were only reduced by 7.6% and 12.6% respectively and thermal stability of PLA-PPy multilayer composite film was significantly improved. Moreover, PLA-PPy/Ag and PLA-PPy multilayer composite film showed similar mechanical properties and thermal stability. More importantly, compared with PLA-PPy multilayer composite film, PLA-PPy/Ag multilayer composite film showed better antibacterial properties, and the total number of Escherichia coli colonies decreased to 2.9×106 CFU/cm2, which was more than 4 orders of magnitude lower than that of the pure PLA film (4.8×1010 CFU/cm2). Compared with the nano silver antibacterial method with high cost, double antibacterial coating (PPy/Ag) with lower cost will have certain research significance in the field of PLA active packaging.