Scarcity of the data on the Cretaceous and Paleogene sporopollen results in a poor understanding of palaeofloras, palaeovegetation, and palaeoecosystem in Tibet. This paper mainly analyzed sporopollen from the Cretaceous and Palaeogene sediments at Cuojiang, Zhongba County, which is located at the southern margin of the Laurasia continent. Two palynological assemblage zones were recognized from the section including, in ascending order, the Classopollis Execipollenites Cycadopites assemblage zone and the Pinuspollenites Quercoidites Trilobapollis assemblage zone. The both can be assigned to late Late Cretaceous or Santonian to Maastrichtian, and Paleogene, or Palaeocene to Eocene respectively. The Cretaceous/Paleogene boundary in this section might possibly locate between the Qubeiya Formation and the Quxia Formation. Pollen of needleleafed trees flourished greatly; but some pollen such as abiespollenites, cedripites, piceapollis and tsugaepollenites were only present at top of the Quxia Formation and base of the Jialazi Formation, suggesting a paleoenvironmental event closely related to a certain tectonic activity, probably the beginning of the collision between Indian and Laurasian plates. The studied palynofloras can be compared with those in south China, but different from those in the northern margin of India, implying that the marine realm between India and Laurasia continents had been isolating floral communication of two continents by Eocene.