Boehmeria nivea (ramie) is a traditional Chinese fibre crop, and provide the longest nature fibre. This study aimed to clonethe complete coding sequences of CesA1 gene from ramie and analyze its express pattern among different ramie tissues, According to the known sequence of BnCesA1(DQ077190), 5′RACE PCR groove primers were designed to amplify the 5′terminal fragment of BnCesA1 using cDNA from ramie selection “Xiangzhu 3”. Then the full length gene sequence was assembled and cloned. The whole jointed sequence spans 3 253 bp and has an open reading frame of 3 246 bp, which codes for a protein of 1 082 amino acids. Nuclear acid sequence analysis and protein domain comparison indicate that BnCesA1 has a very high homology with Populus trichocarpa, Populus tremuloides,Eucalyptus camaldulensis,Acacia mangium. Specific primers were designed according 5′sequence of BnCesA1 for semi-quantitative RT-PCR analysis to detect the BnCesA1 expression pattern among different ramie tissues. The result demonstrated that BnCesA1 are expressed in various tissues of “Xiangzhu 3”. And the expression level in tissues from high to low is stem, leaf, bud and root. Altogether, our research cloned the first full-length coding sequence of ramie cellulose synthesase,and the higher expression of BnCesA1 in bark suggest that this gene may play an important role in bast fibre synthesis of ramie .