Abstract: Shajingzi structural belt is located in the transition zone between Keping fault-uplift and Awati sag in the northwestern margin of Tarim Basin, as a key area for the Lower Paleozoic hydrocarbon exploration. In order to slove several problems, including ambiguous hydrocarbon sources, uncertain effectiveness of reservoirs and caprocks, and complex accumulation processes in the Cambrian-Silurian strata, by integrating core observation, geochemical analyses, and 2D basin modeling, the authors analyzed the petroleum geological conditions and accumulation evolution of the Lower Paleozoic in this structural belt. The results showed that two sets of effective source rocks were developed in the Lower Paleozoic. The Lower Cambrian Yu'ertusi Formation served as the high-quality main hydrocarbon-generating layer, and the Middle-Upper Ordovician Saergan Formation acted as an important supplement, with the original kerogen predominantly being Type I-II. The sandstones of the Silurian Kepingtage Formation and the Ordovician carbonates constitute effective fracture-pore reservoirs, while the mudstones of the Silurian Yimugantawu Formation and the gypsum-salt rocks of the Cambrian Awatage Formation provided regional high-quality seals. The accumulation evolution modeling revealed a process of "early oil generation (the Late Caledonian to the Early Hercynian) and late gas generation via oil cracking (the Middle Hercynian and thereafter)". A composite hydrocarbon accumulation model of "dual-source hydrocarbon supply, fault-conduit migration, hydrothermal coupling, early oil and late gas" was established for Shajingzi structural belt. The study revealed a natural gas-dominated pattern characterized by "deep in-situ gas generation and shallow fault-migrated gas accumulation". It indicates that the low-amplitude uplifts near deep large fault zones and Himalayan tectonic uplift regions are favorable targets for deep to mid-shallow natural gas exploration, which has guiding implications for the deployment of deep hydrocarbon exploration in the northwestern margin of Tarim Basin.