Abstract: Single fiber of Mao bamboo was extracted by chemical method.Its morphology,microfiber structure and crystalline structure were investigated and compared with those of cotton and flax and ramie fibers by optical microscopy,scanning electron microscope and X-ray diffraction analysis.The investigation showed that bamboo fiber is long cylindrical and uniform in size with distinct nodes,which is similar to flax and ramie fibers,however its length is far less than that of cotton,ramie and flax fibers.Bamboo fiber has a small orientation angle for the exterior microfibers,which are parallel to fiber axis approximately.The structure of concentric lamina in cross section of bamboo fiber had been observed by SEM.The result of X-ray diffraction analysis indicated that crystallinity and orientation of bamboo fibers were similar to those of ramie fibers,and more than those of cotton and flax fibers,in addition,crystallite size of bamboo fiber was biggest among the four fibers.The allomorph in bamboo fibers was determined as I-βdominant type.