Abstract: The surface of ramie fabrics was modified by using four sorts of methods including alkali treatment, silane coupling agent treatment, alkali+silane coupling agent treatment, alkali+flame retardant+silane coupling agent treatment. Then ramie fabrics reinforced thermosetting polylactic acid (PLA) composites were prepared by means of compression molding technology. The effects of the four surface modification methods on flexural properties of ramie fabrics/PLA composites were studied. SEM was used to describe the interface bonding condition between ramie fiber and PLA matrix. The results reveal that after treating ramie fabrics using the four surface modification methods, the flexural properties of ramie fabrics/PLA composites all increase, especially, the increase of flexural strength and modulus is the most with alkali+silane coupling agent treatment, and increases 59.5%, 51.9%, respectively. Alkali+flame retardant+silane coupling agent treatment improves the flexural strength and modulus by 38.0%, 66.8%, and the burn length is 8.25 cm when the ignition time of ramie fabrics/PLA composites is 60 s, which reaches the demand of American standard DOT/FAA/AR-00/12. The results of SEM show that a better interface adhesion occurs between fiber and resin in ramie fabrics/PLA composites after modification treatment.