Abstract: An Early Cretaceous flora from the Longjiang basin on the eastern slope of middle Da Hinggan Mountains is reported. The flora consists at least of 31 species of 18 genera in magafossils and 17 species of 21 genera of palynofossils, and is predominated by artic-ulatae, ferns, ginkgoales and czekanowskiales, followed by bennettitales, cycadoales and Carpolithus, which are probably early-middle Early Cretaceous in age. According to the plant characteristics and associated biological characteristics of Jehol Biota, the Longjiang ba-sin seems to have experienced warm and humid temperate seasonal changes, accompanied by a brief arid, semi-arid climate in the ear-ly-middle Early Cretaceous in general. The paleoenvironment of Longjiang basin should be the lake marsh environment with differ-ent biomes in the wetlands and hillside.