Analysis of 13 spore-pollen assemblage zones reflecting environmental changes since the later middle Pleistocene showed the succession of paleovegetation and the paleogeographic changes in the Bohai Basin and circumjacent area. Paleoclimatic variations here can obviously be divided into 5 cold and 5 warm periods : 2 cold and 1 warm periods in 200 ,000-100, 000 a B . P. (late middle Pleistocene ) 3 cold and 3 warm periods in 100 , 000-12 , 000 a B. P. (late Pleistocene), and 1 warm period since 12 ,000 a B. P. Late Pleistocene climate tended to become colder and colder. The coldest period was in the later stage of late Pleistocene, when the study area was a periglacial zone. The mean annual temperature then was about 10℃ lower than it is now. In the middle stage of late Pleistocene, climate became warm ; the mean annual temperature then was about 3 - 4℃ higher than it is now.By applying principles of climatic stratigraphy, the authors deduced through spore-pollen analysis , that the boundary between mi Analysis of 13 spore-pollen assemblage zones reflecting environmental changes since the later middle Pleistocene showed the succession of paleovegetation and the paleogeographic changes in the Bohai Basin and circumjacent area. Paleoclimatic variations here can obviously be divided into 5 cold and 5 warm periods: 2 cold and 1 warm periods in 200, 000-100, 000 a B. P. (late middle Pleistocene) 3 cold and 3 warm periods in 100, 000-12, 000 a BP (late Pleistocene), and 1 warm period since 12, 000 a BP Late Pleistocene climate tended to become colder and colder. The coldest period was in the later stage of late Pleistocene, when the study area was a perigelacial zone. The mean annual temperature then was about 10 ° C lower than it is now. In the middle stage of late Pleistocene, the climate was warm; the mean annual temperature then was about 3 - 4 ° C higher than it is now. By applying principles of climatic stratigraphy, the authors deduced through spore-pollen analysis, that the boundary between mi