Abstract: Having calibrated, correlated and comprehensively studied the seismic and downhole data from southwestem area in Tarim basin, this article shows that there might be a Sinian between Bachu uplft and Tazhong uplift; the distribution of Middle and Upper Ordovician in south side of the southwest depression of Tarim basin remains not clear; while Lower Carboniferous lies almost in its west part. Also, it is confirmed that Kalashayi formation in Bachu area is not the same one as that determined by Kalashayi profile.

Key words: Tarim basin, Southwest, Seismic sequence, Stratigraphic sequence, Stratigraphic classification, Geologic era, Analysis