Abstract: TRIAP1 can participate in vivo responses by inhibiting apoptosis. In order to analyze the expression regulation of TRIAP1 and miRNAs that regulate TRIAP1's expression under Vibrio harveyi challenge in Penaeus monodon, we obtained the P. monodon TRIAP1 gene (PmTRIAP1) cDNA by RACE, then detected the tissue distribution of PmTRIAP1 by quantitative real-time PCR (qRT-PCR), and investigated the expression association between PmTRIAP1 and its related miRNAs under V. harveyi challenge. The results show that the full-length PmTRIAP1 cDNA sequence was 2 522 bp, containing an 11 bp 5' non-coding region (UTR), a 2 289 bp 3'-UTR and a 222 bp open reading frame encoding 73 amino acids. The qRT-PCR analysis shows that PmTRIAP1 was ubiquitously expressed in all the tested tissues and the highest expression level was obtained in hemocyte. The expression of PmTRIAP1 decreased significantly; however, the expressions of Pm-miR-145-3p and Pm-miR-454-3p increased significantly under V. harveyi challenge, which suggests that the expression levels of PmTRIAP1 and Pm-miR-145-3p, Pm-miR-454-3p were negatively correlated. Dual luciferase reporter assay shows that Pm-miR-145-3p and Pm-miR-454-3p can bind PmTRIAP1 3'UTR to reduce luciferase activity. It is suggested that both Pm-miR-145-3p and Pm-miR-454-3p can target regulate the expression of PmTRIAP1.