Abstract: leptin is an important hormone involved in the regulation of feeding, reproduction and energy consumption in animals, and it also can maintain body energy homeostasis by curbing appetite and promoting energy metabolism in vertebrates. Most fishes have the double leptin genes. In this research, the coding region of leptin A was cloned using PCR reaction in Micropterus salmoides, and the results showed that its open reading frame (ORF) was 486 bp, encoding 161 amino acid proteins. Compared with other species, it was found that the conservative property of leptin in Perciformes reached up to 91.46%, there is almost no gene specific mutation site in leptin A of M. salmoides, and the amino acid sequence of leptin A in M. salmoides had the highest homology with the Siniperca chuatsi (92.59%), followed by the Lateolabrax japonicus(89.51%), Trachinotus blochii (87.04%) and Epinephelus coioides (83.87%). Then, leptin A gene was also detected to be highly expressed in liver by fluorescence quantitative PCR (qPCR), subsequently in heart, head kidney, brain, middle kidney, intestine, spleen, gill, muscle and gonad. In addition, acute hypoxic stress was designed to detect the expression of leptin A (1.2±0.2) mg/L and (3.5±0.2) mg/L. The results showed that at the beginning of hypoxia, the expression level of leptin A in the extreme hypoxia group and the moderate hypoxia group was significantly higher than that in the control group, and this indicates that acute hypoxia can induce leptin A expression in liver. In summary, leptin A of M. salmoides has the highest homology with Siniperca chuatsi(92.59%); leptin A was significantly expressed in the liver of M. salmoides; acute hypoxic stress can significantly induce the expression of leptin A.