Abstract: In order to fully understand the molecular characteristics and expression patterns of expansin genes in moso bamboo（Phyllostachys edulis）,bioinformatics methods were used in this study,and a total of 43 members of the expansin gene family was identified from the genome of moso bamboo,and the members were divided into four subfamilies（EXPA,EXPB,EXLA and EXLB）,which contained 18,17,7 and 1 members respectively,and distributed on 37 Scaffolds. Except that PeEXPA1 had no introns and PeEXLB1 had 11 introns,other expansin genes have 1 to 5 introns respectively. The amino acid length of the expansin was 91～508 aa respectively,all amino acids had high-frequency codons,and most of the expansins were basic and hydrophilic. Protein structure analysis showed that most of the expansins of moso bamboo accounted for the smallest proportion of β-turns and the largest proportion of β-sheets in the secondary structure. The tertiary structure of most members in each subfamily was similar. The qRT-PCR results of 18 EXPA subfamily members showed that their expression were significantly different in different tissues,and the highest expression values were found in leaves except PeEXPA2 and PeEXPA6,indicating that they might play an important role in the growth of leaves.