Light microscopy, scanning electron microscopy and transmission electron microscopy were used to observe the skin microstructure and ultrastructure of the adult Trachidermus fasciatus. The results show that the thickness of the skin in different parts of the body is different, but the basic structure is similar. Skin is composed of epidermis and dermis layers. There is no scale on the skin, and the epidermis layer is thinner, consisting of 4 to 8 layers of cells including epithelial cells and mucous cells and basal cells. The surface cells are flat or polygonal, and they are mainly connected by desmosomes, where the joint forms ridge-like processes. The free surface of epidermal cells invaginate to form some fingerprint-like micro-crests. Mucous cells are spherical,ovoid in shape and distribute between epithelial cells. The primitive mucous granules in mucous cells have different shapes, showing elliptic granules, uniform blocks and loose filaments. Epidermis and dermis are connected through basilar membrane, and dermis is composed of stratum spongiosum and stratum compactum. Dermal connective tissue is thick in the abdomen and thin in other parts. The joint of epidermis and dermis has pigment layer, and the skin of head, backside, tail handle and body side contains more pigment cells than that of abdomen and mentum. In the dermal layer there are dermal keratinized spines in the Yellow River group, but such structures are absent in Luanhe River group. Lateral-line hole and superficial neuromast distribute in the skin of head, body side and tail handle