Abstract: Leptin is encoded by obsese gene is an adipocyte-secreted cytokine. The main function of it is to regulate the balance of energy through the signal transduction pathway and it has a strong relationship with the function of reproduction, organism immune. PCR-SSCP and SYBGREEN Q-PCR was used to analyze the polymorphism of leptin gene and expression difference in 139 samples of Luxi (LX) cattle breeds. The association of variations of leptin gene with growth traits was analyzed. Some indexes of the individuals with genotype BB were higher than that with genotype AA and AB in LX breed such as the indexes of body length, heart length, body weight, hucklebone width, body height. Leptin express high in the white adipose tissue but there is little expression in the organ or the tissue such as heart, liver, kidney, spleen, lung and muscle. These results may be applied to Marker-Assisted Selection (MAS) of Chinese LX cattle breeds improving the economic traits of cattle.