This paper analysed and inferred the features of palaophytes and palaeocli- mate during Pleistocene in the Poplar Valley on the Urumuqi River

and their evo- lutionary processes in the light of the information of the sporo-pollen assemblages obtained from six stages of terraces in the Poplar Valley and the distribution of vemedern vegetation and the climatic law of the northern slope of Tianshan Mountains as well. According to the characteristies of the sporo-pollen assemblages eleven zones may be divided

which represent four cold and two drywarm climatic peri- ods. The variation of vegetation showed that the coldest period was in the First Glacial Period.