Abstract: There is a set of Paleozoic low-grade metamorphosed strata found in Horqin Right Wing Middle Banner area of eastern Inner Mongolia. Due to lack of macrofossils, the low-grade metamorphosed strata were assigned to Permian only on the basis of regional correlation of lithologic combinations. During the 1∶50000 regional geological survey completed in recent years, 9 genera acritarch fossils were found in the strata. Based on a comparative study of the 9 genera acritarch fossils and the known acritarch assemblages of Paleozoic strata at home and abroad, the authors have reached the conclusion that the acritarch fossil assemblage discovered in the study area should have the biological combination features of the Early Cambrian, and hence the stratigraphic age should be Early Cambrian. The identification of Lower Cambrian strata in the study area can provide new information for further study of Paleozoic tectonic evolution in the middle-southern segment of the Da Hinggan Mountains.