The Upper Cretaceous in Songliao Basin contains abundant trace fossils. Based on the observation of cores of 20 wells, 6 types of trace fossils including 15 genera and 20 species are identified in the basin. According to the distribution of these trace fossils in Songliao Basin, 5 ichnoassemblages in the Upper Cretaceous are distinguished as: (1) Scoyenia ichnoassemblage, which mainly includes Scoyenia gracilis, Skolithos, Planolites and Cubichnia, represents shallow water sedimentary environments with periodical exposure; (2)Skolithos ichnoassemblage, which is characterized by the abundance of Skolithos and Cylindricum with low diversity, reflects high energy environments; (3)Arenicolites ichnoassemblage, which is composed of Arenicolites, Polykladichnus, Skolithos, Planolites, Thalassinoides and Fugichnia with high diversity, represents shallow low energy environments; (4)Planolites ichnoassemblage, which is dominated by rich Planolites and Chondrites with low diversity, indicates anoxic quiet water environments; (5)Fuersichnus ichnoassemblage, which contains Fuersichnus, Glockeria, Gordia, Megagrapton and Planolites, suggests deep and relatively quiet water environments.