Abstract: The aim of this experiment is to study the expression and immunolocalization of Endothelin receptor B in alpaca skin, to compare the expression quantity in different colors, and to explore the function of EDNRB in the process of coat color formation. The whole testes were obtained from adult alpaca of white and brown hair colors. The mRNA and protein expression level of EDNRB in alpaca skin of different colors were examined by immunohistochemistry, Real-time quantitative PCR and Western blot. The results showed that the EDNRB gene was expressed in alpaca skin reliably. The expressive quantity of EDNRB gene in the brown alpaca skin tissue was 2.165 1 times than that in white one. The distribution of EDNRB in alpaca skin were demonstrated, the expression was notable difference between the white and brown alpaca based on the average optical density. Our findings showed that EDNRB was closely related to the activity of alpaca melanocytes, and was involved in the formation of alpaca hair and skin color.