The interaction between the east and the west in prehistoric times and its influence on the change of human production mode is a frontier scientific problem.Gansu-Qinghai region is a key area of cultural interaction between the east and the west.Archaeological studies show that the intercontinental cultural interaction in this region began in the Qijia culture period(4300~3500 a B.P.)belonged to the Copper-Stone Age,and the production mode of the ancestors of Qijia culture from the early(4300 ~4000 a B.P.)to the late(4000 ~ 3500 a B.P.)changed significantly.However,the research on plant archaeology that has been carried out mainly focuses on western Gansu and eastern Qinghai,while the research on central and eastern Gansu is relatively weak,resulting in the spatiotemporal variation process of agricultural structure in the period of Qijia culture and its influencing factors are still unclear.In view of the above problems,this paper analyzes the temporal and spatial differences and its influencing factors of the agricultural structure in the Qijia culture period in Gansu-Qinghai region by studying the plant macrofossils at the sites of Qijia culture period in central and eastern Gansu Province.We collected 7 sites of Qijia culture that included Shangmiangua site (35.64°N,107.13°E),Buzihao site (35.71°N,107.30°E),Houhemagougou site(35.634°N,107.27°E)in Zhenyuan County,Dongpo site(35.26°N,107.57°E),Qiaocun site(35.15°N,107.49°E),Jiangjiazui site (35.04°N,107.44°E)in Lingtai County on eastern Gansu and Guanzizui site in Lintao County on central Gansu.We got 23 soil samples on central and eastern Gansu Province.13567 of charred plant seeds were identified respectively.Based on the flotation method and AMS 14C chronometry,The results showed that in the early period of the Qijia culture,the agricultural structure in the east and west of the Gansu-Qinghai region was dominated by foxtail millet and supplemented by broomcorn millet,which may be related to the high yield of foxtail millet and the high efficiency of water usage.In the late period of Qijia culture,wheat and barley originated in West Asia were introduced into the Gansu-Qinghai region,and the agricultural structure in the west was changed to mainly millet agriculture and supplemented by wheat agriculture.However,in the eastern part of Gansu,a single agricultural structure dominated by millet was continued,which may be related to different regions' responses to climate change.Millet can satisfy people's demand.This study shows that the spatiotemporal variation of crop planting structure during the Qijia culture period in the Gansu-Qinghai region is affected by the interaction between the prehistoric east and the west,climate change and local environment and other factors,which is helpful to understand the process and mechanism of the evolution of human-land relations in the key period of the communication between the prehistoric east and the west.