目的 研究纤维表面改性对复合材料结晶、热稳定性、动态力学性能、尺寸稳定性、吸水率等的影响。方法 采用碱、碱+马来酸酐、碱+KH550这3种处理方法对纤维表面进行改性，通过熔融挤出与聚乳酸（PLA）混合制备聚乳酸/亚麻纤维（PLA/Flax）复合材料。结果 亚麻纤维经表面改性后使PLA更容易发生冷结晶，结晶结构更加致密、完善，PLA/Flax尺寸稳定性优于PLA。纤维的加入提高了PLA的吸水率，但热稳定性能有所降低。纤维表面改性降低了PLA/Flax的储能模量。结论 碱+KH550处理纤维与PLA共混所得复合材料的结晶性、尺寸稳定性最佳，为高性能PLA/Flax复合材料的制备提供了一定的实验及理论依据。

The work aims to study the effect of fiber surface modification on the crystallization, thermal stability, dynamic mechanical performance, dimensional stability and water absorption of the composites. The fiber surface was modified by alkali, alkali+maleic anhydride and alkali+KH550. The PLA (polylactic acid)/Flax composites were prepared by mixing the PLA through the melting extrusion. The introduction of flax fibers with modified surface made it easier for PLA cold crystallization, and made the crystalline structure more compact and perfect. The dimensional stability of PLA/Flax composite was better than that of the PLA. The incorporation of fibers improved the water absorption of PLA, but lowered its thermal stability. Through fiber surface modification, the energy storage modulus of PLA/Flax reduced. The crystallinity and dimensional stability of composites prepared by the mixture of the fibers treated by alkali+KH550 and the PLA are the best, which provides certain experimental and theoretical basis for the preparation of the high-performance PLA/Flax composite.