Leptin, an adipocyte-derived hormone, plays important roles in metabolism and reproduction. In this article, we report the cloning, expression, and identification of the giant panda leptin (gLeptin) gene and its variants. The gLeptin cDNA was 504 bp long, encoding a precursor peptide of 167 amino acids including 21 residues of signal peptide. A short variant of gLeptin was 501 bp long, encoding a 166-aa peptide and also including a 21-aa signal peptide. Giant panda leptin was 99.4%, 94.6%, and 92.8% identical to that of black bear, dog, and cat, respectively, but was only 81.4% and 80.8% identical to that of human and rat. The cloned gLeptin gene was expressed in Escherichia coli, with expression confirmed by Western blotting and MALDI-TOF-TOF MS PMF. After purification, renaturation, and condensation, the gLeptin protein was injected into Kunming mice. The recombinant gLeptin significantly inhibited food intake by 41.8% and reduced body weight by 5.1% in the mice.