Abstract: The peat-bogs in Mount Hsishan, Nan. chang, is widely distributed. It is one of the typical peat-bogs in South China. For palynological study, the author has collected some samples from three boring cores, and has found pollen and spores of many species. In the assemblages, Pinus and Castanopsis are absolutely predominant in number, and there are also some of Liquidambar, Alnus, Eurya, Salix, Ilex, Quercus, Myrica, Sapium, Cunninghamia and others. Herbaceous pollen and spores in assemblages are rare, and in a subordinate position, in which are mostly pollen of Gramineae and Compositae, and a certain number of pollen of aquatic plants. As to spores, Pteridium and Polypodiaceae are in large numbers. The data of the palynological assemblages indicate that the flora was evergreen forest of broad-leaved trees evergeen forest of conifer, and with some few mixed forest of broad-leaved dediduous trees. The data of polynological analysis of Siyao Lake distinctly shows that there are four stages in the vegetative evolution in the district of Mount Itsishan in Itolocene: first stage recorded the forest dominated by Castanopsis; second stage, the foresr dominated by Pinus; third stage, mixed forest dominated by Alnus and Pinus, fourth stage, mixed forest with some Castanopsis and Quercus. Inferring from the above mentioned fact, it is to be assumed that the age of the formation of peat-bogs in Mount Hsishan began from the Atlantic stage of Holocene.