Abstract: During the 1:50000 regional geological survey in Jarud Qi from 2006 to 2008, the Early Carboniferous fossil plant of Archaeocalamites sp. was obtained from the gray-black silty tuffaceous silicon-pelitic slate in the lower part of the formation. Its age had been originally considered as the Early Permian. Based on the stratigraphic correlation and paleontological characteristics, the formation that includes plant fossils of Archaeocalamites sp. is revised as Late DevonianEarly Carboniferous, and assigned to Seribayanaobao Formation.