Abstract: According to principle of continental sequence stratigraphy and specific property of alluvial system, applying principle about base-level cycle in high resolution sequence stratigraphy, this paper studied the relation between accommodating space growth rate and sedi-ment supply rate,by which the characteristics of system tract and deposit system in various conditions were defined. It is concluded that a complet set of sequenses should consist of several system tracts such as alluvial filling, transgressive and regressive, and fluvial ones. Note that transgressive and regressive system tracts are not developed instead of alluvial filling and fluvial system tracts when remainder accommo-dation space is not enough; while upper fluvial system tract is hard to remain because of denudation from the continuous falling of datum level. Furthermore, four sequences have been defined based on study of Cangfanggou and Xiaoquangou groups in east Junggar basin. In Se-quence A and D, transgressive and regressive system tracts are developed; in Sequence B and C, alluvial flling and fluvial system tracts de-veloped

Key words: Junggar basin, Permian, Triassic, sequence stratigraphy