The Jimunai Zaysan basin is an important Permian petroliferous basin with low degree of exploration in the western part of the paleo Asian Ocean structural domain, with limited study of hydrocarbon accumulation. Based on regional geology, geological outcrops, core, lab tests, and seismic data, the petroleum geological conditions of generation, storage, cover, circle, transportation and preservation were analyzed. From this, the hydrocarbon generation process, driving forces for expulsion, reservoir forming power and mode were studied, the event chart of petroleum system was drawn, the hydrocarbon accumulation process with its model were comprehensively analyzed and summarized. Two sets of main Permian source rocks are developed in the Jimunai—Zaysan basin: ① Lower Permian shallow lake dark mudstones in the Kalagang Formation or the Акансайская Formation is one set of source rocks, which is mainly distributed in the piedmont area in the south of basin, and developed in a fresh water lake with slight anoxic environment. The content of TOC is 0. 936%, S 1+S 2 is 0. 086 mg/g, kerogen type is Ⅱ 2 Ⅲ, R o is 1. 54%, and organic matter are basically at maturity & over maturity stage. ② Upper Permian semi deep to deep lake dark oil shale and the mudstone Maichat Formation is another set of source rocks, which mainly distributed in the central part of the Zaysan depression, and developed in saline and strongly reducing environment. Kerogen type is Ⅰ, R o is 0. 68%, the color change index of sporopollen is 2. 83, organic matter is in the low mature stage of oil generation window. The reservoir mainly consists of Permian sandstone and conglomerate. The shale of the Maichat Formation and the Kalagang Formation are important caprocks. The traps are mainly in the form of lithology, anticline, fault nose, fault block and horst. There were two types of oil and gas migration pathways, one was normal fault and magmatic cleavage short distance vertical migration pathway, the other was unconformity surface long distance lateral migration pathway. The main source rocks have undergone multiple hydrocarbon generation and expulsion processes; the oil generation peak was in the early Jurassic, and the gas generation peak was in the Paleogene. Under the driver of abnormal overpressure, oil entered into the close range Permian lithologic trap, and formed a reservoir. Through vertical short distance migration pathways such as faults and magma bottom splits, oil and gas was enriched in traps such as fault anticline and bottom splitting structure. By long distance lateral migration, gas accumulated at unconformity between Paleogene and underlying strata.