Abstract: The Kuluktak area is located the northeastern margin of Tarim Basin. The Ordovician sequences bounded by the Xingdi Fault can be divided into two sedimentary facles regions, among which the Ordovician sequence in mouthern region consists of abymal facles tarreatrial clastic turbidite and the northern one' dominated by open-marine continent shelf platform facles carbonate. In terms of the abmence of the top of middle Ordovician, the middle and upper Ordovician showing angulat intersoctian, and the preence of weathered residue, it is concluded that the middle and upper Ordoviclan formations in southern region are unconformable contact. The tectionic movement resulting in the unconformity is named as Yacrdangshan movement.