It is necessary to understand the molecular mechanism of banana dwarfing mutation in order to improve the high stem character of banana varieties and breed the new excellent dwarf lines. To elucidate the molecular-level regulation of banana dwarf mutations and identify the relevant genes, the complete cDNA sequence of the gibberellin 2-oxidase gene (GA2ox) in the dwarf banana and its wild type was cloned by RT-PCR and the encoded amino acid sequences bioinformatically was analyzed. Meanwhile, the expression levels of banana GA2ox gene in different tissues of dwarfed banana and its wild type were analyzed by qRT-PCR. Between the GA2ox gene sequences of the dwarf banana and its wildtype, there were 5 base pairs of variation, leading to the predicted GA2ox proteins having different molecular weights, isoelectric points, fat indices, total numbers of positive and negative charges, and hydrophilicity. In addition, the expression of GA2ox in the leaves, stalks, and fruits of dwarf banana plants was higher than that in the wild type in the early and middle stages of banana development. The results showed that the GA2ox gene may have important regulatory effects on banana stem dwarfing, the knowledge of which can help our understanding and manipulation of this important plant.