The synthetic analyses based on paleontologic stratigraphy, paleomagnetics, petrogeo-chemistry, and isotopic ages show that a paleo-ocean should have existed in Southern Tianshan during the Ordovician-Permian. The earliest rifting was marked by the continental rift eruption of the Sinian Beiyixi Formation (Z1b). From the Sinian to Ordovician, the evolution from a rift to a passive continental-margin ocean-basin was completed in the Silurian and Devonian, the oceanic crust of southern Tianshan began to be subducted beneath the Kasakstan plate. In the terminal Devonian to the Early Carboniferous, the oceanic crust was consumed at all, so the continent-continent collision occurred between the Tarim and Kasakstan plates. In the Carboniferous-Early Permian a sea basin opening to the west still existed in Southern Tianshan and it was closed finally in the Permian.