Abstract: Permian and Triassic are the key periods for tectonic evolution in Junggar basin, but there are lots of disputes on the understanding of the tectonic evolution. Aiming at Triassic series of Sikeshu sag, the paper performs provenance analysis by combining the data of sedimentary environment, paleocurrent direction, gravel composition, detrital component of sandstone and detrital zircon age of U-Pb, and discusses the tectonic evolution history of the southern margin of Junggar basin during Triassic period. The composite analysis shows that the orogenic belts of North Tianshan Mountains and the northern margin of the central Tianshan Mountains are the major provenances of the upper Cangfanggou group of the Lower Triassic in Sikeshu sag, and the South Tianshan Mountains and the southern margin of Central Tianshan Mountains are the minor provenances. The variations of the provenances during Middle-Late Triassic epochs can be attributed to the subsidence of sedimentary basin resulted from the occurrence of depression in the southern margin of Junggar basin, which was the initiation of Sikeshu sag, indicating that Middle-Late Triassic epochs are the key periods for the down-wraped basin evolution in the southern margin of Junggar basin