To study the structural characteristics of Langerhans cells (LCs) and the effect of bacterial infection on the expression of functional genes of LCs in yellow catfish,the LCs in immune tissues of yellow catfish were identified by immunohistochemical (IHC) technique,the ultrastructure of LCs was further observed by transmission electron microscope (TEM) technique,and the expression levels of IL-1β,TNF-α,IL-10 and TLR-4 genes related to the function of LCs in the immunity related tissues of yellow catfish were detected by real-time quantitative PCR in this study. The results showed that the CD207 protein,a specific molecular marker for LCs,were detected in the head kidney and spleen,and the structure of the yellow catfish LCs was similar to that of other vertebrates,with granules arranged radially around the centriole in cytoplasm. The expression levels of the IL-1β,TNF-α,IL-10 and TLR-4 genes in the immunity related tissues of yellow catfish were significantly up-regulated after Edwardsiella ictaluri infection. The above results indicated that the LCs were distributed in yellow catfish,and they may participate in the body′s immune response against E. ictaluri infection.