Abstract: In order to study the structure and biological function of the alpha-amylase gene in Penaeus monodon, the full-length cDNA sequence of α-Amylase from Penaeus monodon (PmAmy) was obtained by high throughput transcriptome sequencing and RACE. The PmAmy cDNA included an open reading frame of 2175 bp encoding a polypeptide of 724 amino acids, and the predicted molecular mass and isoelectric point were 78.9 kD and 4.66, respectively. The PmAmy contained a conservative A domain (Thr³⁴-Ser⁴¹⁰) and a C domain (Glu⁴²⁰-Ala⁴⁹⁶) of alpha amylase family. Homology analysis revealed that the PmAmy shared 47%—99% identity to other known amylase sequences, and the phylogenetic tree showed that the PmAmy was closely related to Litopenaeus vannamei. The expression levels of PmAmy in hepatopancreas were significantly higher than those of the other tissues (P<0.05). ThePmAmy expression was found in five ovarian development stages. The expression level in yolky stage (stageⅣ) was the highest among the five stages, and was the lowest in ovogonium stage (stageⅠ). The expression levels of PmAmy showed no significantly difference in ovary development stages. Expression of PmAmy was detected in all tested growth stages, and the expression level in mysis was significantly higher than that in nauplius, zoea and post larval (P<0.05). These results suggested thatPmAmy might be associated with larval development in P. monodon.