The morphology and structure of Broussonetia papyrifera(BP) bast and fiber were investigated by SEM, OM, FT-IR and X-ray analysis, and chemical composition of BP bast was analyzed. The results show that the cellulose content in the BP bast can be as high as 63.76%. BP fibers arrange parallel in the bast, which are linked by pection. The cross-section of PB fibers are irregular round with lumens that are almost invisible in the completely mature fibers. The crystallinity of the fiber could reach 83.26%. Most impurities such as hemi-cellulose, lignin, pectin could be effectively removed by degumming, while cellulosic structure is not changed. BP fiber has good mechanical properties, but the single fiber is too short to spin alone.