To promote the development and application of multicolor silk,the morphological structure of the nature yellow silkworm silk from a silkworm variety,selected by cross breeding method,was investigated by SEM and compared with the normal white silkworm silk,the golden wild silkworm silk from Cambodia,and the Antheraea pernyi silk,respectively.Results shown that the morphological structure of the nature yellow silkworm silk fiber was triangle,more close to the normal white silkworm silk fiber,the golden wild silkworm silk fiber also was close to triangle,but the Antheraea pernyi silk fiber was close to oval.The gloss of the nature yellow silkworm silk was better than the normal white silkworm silk and the Antheraea pernyi silk.The ionetching experiment results showed that tissue structure of the nature yellow silk was tighter than that of the normal white silkworm silk.