In this paper, the physical and chemical properties of Xinjiang Flax fiber were studied systematically, including mechanical properties by single fiber strength meter, average fineness of single fiber, qualitative and quantitative analysis of chemical composition by infrared spectrophotometer, crystallinity and orientation by X-ray diffractometer, and physical morphology by SEM. The results showed that the main chemical composition and content of Xinjiang Flax fiber were: 1.5969% of fatty wax, 6.6814% of water-soluble matter, 3.5058% of pectin, 17.5510% of hemicellulose and 2.1853% of lignin, the average breaking strength was 228.25cN, the average breaking elongation was 1.04 mm and the average breaking time was 2.09 s, and the average fineness of Xinjiang Flax single fiber was 49.43 μm. The fiber surface is rough and adheres to colloid. The internal molecular structure is relatively close, and the fiber macromolecules are arranged orderly in the crystallization zone, with the crystallinity of 77.5% and the orientation of 91.8%. The above data and analysis provide valuable theoretical basis for the degumming and high-quality yarn spinning of Xinjiang Flax, which is conducive to the further development of Xinjiang Flax.