Abstract: The eastern Junggar Basin has entered the stage of continental basin evolution since the late Carboniferous.It is composed of several hydrocarbon bearing sags and uplifts with complicated tectonic evolution history,which can be divided into 4 stages:rift-faulted basin during Pemian, faulted-depression basin from Triassic to Jurassic,intra-continental depression basin from Cretaceous to Eocene,and rejuvenated foreland basin during late Cenozoic.Tectonic evolution of the Jimsar Sag has great influence on petroleum system formation in the following 3 aspeots:a) Tectonic evolution controls the formation of source rocks and source-reservoir-caprock assemblages;b) Tectonic evolution is likely to postpone the evolution processes of source rocks;c) The most important,tectonic evolution may control the multi-phase hydrocarbon generation and the multi-phase pool forming of every petroleum system,which make up of the critical moments for hydrocarbon migration,accumulation,rebuilding and preservation of composite petroleum system.