Abstract: 【Objective】 To clone a expansin gene ZjEXPA8 and analyze its sequence characteristics analyzed in the hope of laying a foundation for further study on the role and function of the gene in the fruit development of Huizao. 【Methods】 In this study, the flower and young fruit of Huizao were used as the tested materials.According to the sequence of ZjEXPA8 gene (LOC107414006), Primer Premier 5.0 software was used to design primers, and RT-PCR was used to clone ZjEXPA8 gene.In addition, Bioinformatics method was used to analyze the nucleotide sequence of ZjEXPA8 gene. 【Results】 ZjEXPA8 contained a 762 bp open reading frame (gene accession number was NP_001310794.1), which encoded 253 amino acids.The predicted molecular weight of the protein was 26.91 kDa, the isoelectric point was 8.32, the instability coefficient was 30.09, and the fat index was 66.72.The mean total hydrophilicity was -0.107, which belonged to stable hydrophilic protein.The main component of the secondary and tertiary structure of ZjEXPA8 protein was irregular curls.The structure analysis of ZjEXPA8 protein showed that the protein did not have transmembrane domain, but contained two conserved domains of DPBB_1 and Pollen_allerg_1.Homologous sequence alignment analysis showed that ZjEXPA8 protein exhibited the highest similarity with soybean (Glycine Max, XP_003523277.1, GmEXPA8) (93.13%).Phylogenetic tree analysis showed that ZjEXPA8 gene was most closely related to Hevea Brasiliensis (XP_021684783.1, HbEXPA8) and Arabidopsis thaliana (NP_181593.1, AtEXPA8).Real-time quantitative PCR revealed that ZjEXPA8 gene expressed in different flower development stages of Huizao with the highest expression level in bud yellow stage and the second in sepal spread stage, suggesting that ZjEXPA8 gene may mainly play its role in bud yellowing and sepal flattening stage. 【Conclusion】 The protein encoded by ZjEXPA8 exhibits the highest homology with soybean.Phylogenetic tree analysis shows that ZjEXPA8 is closely related to Hevea Brasiliensis (HbEXPA8) and Arabidopsis thaliana (AtEXPA8).