SUN gene is the major gene controlling fruit shape in tomato. In this study, we searched the grape sequence in NCBI, found the highest similar sequence of SUN gene in grape as compared with tomato and designed the specific primer. The cDNA of SUN gene, which is named VvSUN, is cloned by RTPCR technique. Sequence analysis showed that the VvSUN gene contains a 1 278 bp open reading frame (ORF), which encodes a polypeptide of 425 amino acids with a calculated molecular weight of 48.11 kD and an isoelectric point of 10.63. Moreover, the data also indicated that VvSUN is a nontransmembrane and hydrophilic protein and most likely located in the nucleus and mitochondrial membrane, without signal peptide. Secondary structure analysis indicated that αhelix and random coil are the main structural elements in VvSUN protein. The amino acid sequence encoded by VvSUN gene has an IQ conserved domain, and the sequence similarity to other seven plants IQD family members in NCBI is 43%-53%. The phylogenetic tree showed that grape has the closest relationship with Arabidopsis thaliana IQD12 gene. According to these observations, we predicted that VvSUN protein in grape has similar functions with SUN protein in tomato. In addition, we performed quantitative realtime PCR (qRTPCR) to determine the expression pattern of VvSUN in grape at different developmental stages and under gibberellin (GA₃) treatments and used the vertical and horizontal diameters to evaluate the effects of GA₃. Realtime PCR analysis revealed that the expression level of VvSUN gene showed the highest level at anthesis in two varieties, while maintained relatively low levels after anthesis. GA₃ treatments markedly increased the fruit shape index, and pronouncedly enhanced the expression level of VvSUN gene in young fruit. Thus, our results suggested that the VvSUN gene in grape may be involved in the regulation of fruit elongation.