Abstract: A new genus and species of Arthrodira described in this paper was collected from the Upper Devonian of Chongyi, Jiangxi Province, China. The characters of the new genus and species includes the anterior division of the inferognathal toothed and equal to the posterior non-biting division of the inferogathal. The biting division with anterior and posterior dental fields, anterior dental field carrying a front "tooth" which lower than other biting division; the posterior dental field with a posterior row of five teeth on posterodorsal part of the biting division of the inferognathal that stands vertically. The edentulous area concave slightly. New genus and species, Gannanichthys chongyiensis gen. et sp. nov. is erected only by two plates: the inferognathal and anterior lateral plate. It is the first Arthrodira unearthed from Upper Devonian of Jiangxi Province. The Chongyi fossil has provided scientific basis for comparing the stratigraphy and studying paleogeography. The present genus and species is similar to Dinichthys, Dunkleosteus, Eastmansteus and Gorgonichthys in shape of inferognathal, but it differs from them in the smaller size, the front "tooth" lower than other biting division, the cusp of small denticles stands vertically and the edentulous area concave slightly, and in the tatters the anterior part of ventral margin of the biting division not protruding downward into a ventral process. The anterior lateral plate of the new material is very similar to Hardrosteus and Parabelosteus in shape, but the new material differs from them in the smaller size, and dorsal blade longer and ventral blade shorter. The material described is housed in the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences.