Trehalase plays a critical role in metabolic processes by catalyzing the hydrolysis of trehalose to glucose. In this study, we cloned and characterized a full-length cDNA encoding membrane-bound trehalase in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) and named it as BdTre2. BdTre2 contained an open reading frame (ORF) of 1842 bp,which encoded a putative 613 amino acids. Alignment analysis revealed that the deduced protein sequence of BdTre2 had about a 70% identity to Tre2 of most dipteran insects, suggesting that this gene was conserved in the evolution of the Diptera. Phylogenetic analysis showed that the deduced protein of BdTre2 was more homologous to the trehalase2 gene than insect trehalase1 gene. The expression pattern in different developmental stages and tissues of BdTre2 in B. dorsalis was measured by quantitative real-time PCR (qPCR), and the results showed that BdTre2 was strongly expressed in the adult stage, particularly in the midgut. Concurrently, the enzyme activity assay showed that trehalase 2 was more active in the adult stage and Malpighian tubules than in other developmental stages or tissues. Our results provide evidence that BdTre2 is involved in activity of the midgut, possibly in chitin synthesis and energy metabolism, and it is important for B. dorsalis adults.