Abstract: Dual specificity phosphatase 1 (dusp1) is an enzyme to inactivate MAPKs by selectively dephosphorylating critical serine/threonine residues. Dusp1 plays an important role in many environmental stress including hypoxia, oxidative stress, UV and heat shock. However, the role of dusp1 in response to cold stress has been rarely reported in fish species, especially in polar fish. To address this, we cloned a dusp1 homolog gene encoding 376 amino acids from Trematomus bernacchii. The open reading frame encoding dusp1 was amplified by PCR with homologous recombination approach cloned into pcDNA3.1 vector, referred to as pcDNA3.1-dusp1. The constructed eukaryotic expression vector pcDNA3. 1-dusp1 were transferred into the human embryonic kidney 293T (HEK293T) cells, and pcDNA3.1 (empty vector)-transfected cells were used as a negative control. The reactive oxygen species (ROS) was assayed using fluorescence probe DCFH-DA and the survival rate under low temperature stress was detected by flow cytometry, respectively. A Western-blot analysis was applied to determine the phosphorylation of P38/MAPK levels and the apoptosis effector gene caspase-3 mRNA expression levels were measured using RT-qPCR. The results showed the T. bernacchii DUSP1 protein in the HEK293T cells with the subcellular localization at nucleus. Dusp1 over-expression significantly decreased ROS content and apoptosis rate in cells under cold stress, and it also suppressed hyperphosphorylation of the pro-apoptotic gene p38 and decreased caspase-3 transcriptional activity. These results indicated that dusp1 from T. bernacchii can protect cells from the damage under cold stress, and this protection was achieved by inhibiting of the p38MAPK and caspase-3 activation. This study provide new insights of the cold temperature adaptive evolution of polar fish and lay a foundation for further functional studies of dusp1 in teleosts under cold stress.