Many genes that play roles in shrimp vitellogenesis, such as that encoding nuclear autoantigenic sperm protein (NASP), have been identified by suppression subtractive hybridization. In shrimp, NASP plays an important role in ovarian maturation. In this study, the using the rapid amplification of cDNA ends technique. The full-length cDNA of consisted of 2258 bp with a 92-bp 5'-untranslated region (UTR), a 174-bp 3'-UTR, and a 2019-bp open reading frame, which encoded a protein of 673 amino acids with a predicted isoelectric point of 4.46 and a predicted molecular weight of 74.18 kDa. The sequence has been submitted to GenBank under the accession number KT274811. The putative protein had two conserved regions:SHNi-TPR and TPR_2. A sequence alignment analysis revealed that the Penaeus monodon (GenBank accession number:FJ040859.1). We constructed a phylogenetic tree based on NASP sequences to evaluate the evolutionary relationships of NASPs between L. vannamei was in the same branch as that of were investigated in the ovary and hepatopancreas of at different overy developmental stages by real-time fluorescent quantitative PCR. The results showed that transcripts were present at all stages, with the highest levels at the second stage and the lowest levels at the third stage. The NASP transcript levels were higher in the ovary than in the hepatopancreas, in which the transcript level was negligible. These results provide the basis for further research on the role of NASP in ovarian development in .