The East Junggar orogenic belt, a significant segment of the Central Asian orogenic belt, represents an excellent natural laboratory for investigating the spatiotemporal evolution and the orogenic patterns of crustal deformation. This region has undergone complex, multistage evolution since the late Paleozoic, with extensive research focusing on reconstructing its Paleozoic tectonic framework and establishing tectonic evolution models. However, studies on the tectono- thermal evolution of the region remain insufficient, particularly regarding constraints on late Paleozoic exhumation. The Kalamaili Mountain, a prominent tectonic and geomorphological unit in the East Junggar orogenic belt, holds crucial information about the region' s uplift and exhumation history. Investigating its tectono- thermal evolution can provide valuable insights into the broader tectonic processes of the East Junggar. This study presents new zircon (U- Th)/He, apatite (U- Th- Sm)/He, and apatite fission track data from four sedimentary rocks collected from the eastern part of the Kalamaili Mountain. These thermochronological data are used to constrain the late Paleozoic- Mesozoic uplift and exhumation history of the region. Thermal history modeling reveals four distinct episodes of rapid exhumation in the East Junggar, including the Late Carboniferous- Early Permian (330~290 Ma), late Early Permian- Middle Permian (285~260 Ma), Triassic (250~230 Ma) and the Early Cretaceous (135~115 Ma). The first episode may be linked to the closure of the Irtysh- Zaisan in the Late Carboniferous. The second episodeis likely associated with dextral strike- slip deformation of the Kalamaili tectonic belt in the late Paleozoic. The third episode may be interpreted as a response to the distal effects of the collision between the Qiangtang and Kunlun- Qaidam blocks. The last episode is regarded to be the result of the closure of the Mongol- Okhotsk Ocean in the north and the collision between the Qiangtang and Lhasa blocks in the south.