The paper refers to the results of the pollen and spore analysis from the two important areas of Dong Nai and the whole south area of South Vietnam in general: i.e. the bazalt hillock area and the coastal area that belongs to the ecological system of salt - marsh in order to provide more data to study the floral components, stratum structure, and outline natural landscape and ancient living environment of ancient inhabitants of high land areas of South Vietnam in pre-protohistory.The samples were collected from such sites as Cau Sat, Suoi Chon, Go Me, Hang Gon II (78) of Long Khanh district, Suoi (stream), Dam banks and the foot of Hill 57 (Cam My district). The the analytical results demenstrate that in pre-protohistory of south area of South Vietnam, there was a stable background of tropical - semi - tropical hot and dry climate and Holocene floristic composition with the diversity of grass, bushes and primary forests. The existence with a dominant number of Poaceae in all the analised samples are much likely to be associated to cultivated rice and agricultural activity in pre-protohistory.