The nuclear receptor superfamily contains a large number of transcription factors that mediate many physiological process, such as cell differentiation, growth and development. Family members have a conserved functional domain that includes a DNA-binding domain and a ligand-binding domain. HR38, a member of the nuclear receptor superfamily, is an orphan receptor for which no ligand is known. HR38 is involved in an unusual ecdysteroid signaling pathway in Drosophila. is a major Chinese aquaculture species and is also an important Chinese export. The crustacean molting cycle is a physiologically important growth process. To investigate its function in the molting cycle of Portunus trituberculatus was cloned by rapid amplification of cDNA ends (RACE) and named cDNA is 2950 bp, including a 101-bp 5' untranslated region (UTR) and a 551-bp 3' UTR. The 2298-bp open reading frame (ORF) encodes a 765-amino acid polypeptide. Bioinformatic analysis revealed that PTHR38 is anunstable protein and has no transmembrane domains. Homology analysis showed that has the highest homology to the HR38 gene of . Six crabs ateach main molting stage (inter-, pre-and post-molting) were selected by morphological feature observation. Eyestalks were excised, the crabs were depigmented, their exoskeletons were removed, and different tissues were sampled before being stored in Trizol Reagent for RNA extraction. Quantitative real-time PCR showed different expression patterns of PTHR38 functions in the molting cycle of . It also showed a similar expression tendency to ecdysone in hemocytes and thus might be associated with ecdysone. In muscle and the hepatopancreas, was upregulated in the post-molting stage. Previous studies showed that HR38 participates in the metabolism of carbohydrates, which suggested that might function in energy metabolism processes. After eyestalk ablation, the expression of PTHR38 and ecdysone.