A well-preserved fossil pollen flora from the Bose Basin located in mid-western Guangxi, South China (long. 106 degrees 34'-107 degrees 21'E and lat. 23 degrees 28-23 degrees 55'N), consists of some 160 types belonging to 121 genera and 62 families. Four pollen and spore assemblages are recognized (from the bottom upward) for the Late Eocene Nadu Formation: Polypodiaceae-Pinuspollenites assemblage, Quercoidites-Ulmipollenites assemblage, Alnipollenites-Tricolporopollenites assemblage, and Pinuspollenites-Quercoidites assemblage. The pollen flora of the Bose Basin represents a mixed evergreen and deciduous broad-leaved forest that consisted mainly of Fagaceae, Ulmaceae, Betulaceae, and Juglandaceae along with a number of subtropical to tropical evergreen trees. Relatively common occurrence of Pinaceae pollen probably indicates a conifer forest or woodland on the mountain area not far from the lowland sediment basin. This type of paleovegetation is similar to the modern mixed evergreen and deciduous broad-leaved forest in southern China, reflecting a humid southern subtropical climate. Most pollen types in the flora of the Nadu Formation of the Bose Basin are the common elements found in the Lower Tertiary floras of South China. Only a few morphologically extinct pollen types were encountered. Most fossil pollen and spore taxa can be compared with the modern ones in morphology. Many important families of the modern floras in the subtropical and tropical areas of southern China occur in the Upper Eocene fossil pollen flora of the Bose Basin. This probably suggests a floral modernization in southern China during or before the Late Eocene. Since the pollen and spore assemblages from the exposed sections in the basin can be compared with those from the drill cores, pollen analysis becomes a main tool in the correlation and age determination for the core samples in the energy exploration in the Bose Basin of Guangxi, South China.