Abstract: According to the conservative sequences of announced obese gene in human ，mouse and pig, a pair of primers were designed. The obese gene of the duck was amplified by RT-PCR. The product was cloned into pGEM-T vector. Sequence analysis revealed that it has a length of 438 nucleotides which encods a 146-amino peptide. When nucleotid sequence and deduced amino acid sequence were compared with homologous sequence of human, pig and rat, it displayed a fairly high degree of conservation. The homologue of the nucleotide sequence are 83%，84%，98% and 94% respectively; the homologue of the amino acid sequence are 86%，83%，99% and 96% respectively. With the aim of analyzing the characteristic of the expression, the cDNA fragment was inserted into expression vector pET-28a and the resulted plasmids were expressed in E.coli BL21(DE3) by IPTG induction. The results of SDS-PAGE analysis indicated that protein was specifically expressed in the E.coli BL21(DE3).The weight of the fusion protein was about 20 ku,which included the 16 ku protein expressed from duck obese gene. The cloning and expression of the duck obese gene established the foundation of the further research about the function and application of the duck leptin.