Abstract: The Guanjiagou Formation is exposed extensively in West Qinling, Gansu Province. The Guanjiagou Formation is mainly composed of slightly metamorphosed clastic rocks, and its age is a topic of controversy. 8 genera and 18 species of cyptospores and miospores, 8 genera and 10 species of Acritarchs, 3 genera and 4 species of chitinozoa and 3 genera (3 species) of scolecondonts were recognized. The oldest geologically well-dated spore tetrads and cuticlolike sheets of cell have been recovered from the Guanjiagou Formation, Wenxian County, Gansu Province. This is the first record of genera and species in China, and is the earliest known occurrence of land plant spores in China. The species is a typical Late Ordovician element known currently from Europe, Africa, North America and South America. The age of the cryptospores and miospores may also be Late Ordovician, equivalent to the Caradocian and Ashgillian.