Abstract: The dispute about the Jurassic sedimentary boundary between the Junggar and Turpan-Hami Basins has lasted for a long time,focusing mainly on sedimentological issues.In this paper,the further study of the sedimentary boundary was made on the basis of the studies of the Jurassic sedimentary facies,palaeocurrent direction,sediment sources on the northern and southern margins of the Bogda Mountain area,in combination with regional tectonic settings.It is believed that the two basins cited above were once separated by the Bogda Mountains at least before Jurassic time,since then there were also substantial variations in sedimentary and tectonic evolutionary history in the two basins.