Abstract: The Xujiaweizi Fault Depression is the most abundant area of deep natural gas in the northern part of the Songliao Basin, and it is also the most explored gas-bearing fault depression in the region. The Lower Cretaceous Shahezi Formation serve as the primary hydrocarbon source rock of the Xujiaweizi Fault Depression within the Songliao Basin, making it crucial of the investigation of its geological and geophysical characteristics for the exploration and exploitation of deep-seated resources. The Well SK2, located in northeast China, is drilled to a depth of 7 018 m, yielding the most complete and continuous core of the fault depression, which provide essential data for the analysis of the Shahezi Formation’s stratigraphy. This study redefines the stratigraphic sequence and deep resource attributes of the Shahezi Formation based on the latest cores testing and logging outcomes from the Well SK2. The top and bottom ages of the Shahezi Formation revealed by the Well SK2 are about 112 Ma and 118 Ma, respectively, which belong to the middle Aptian-early Albian period, which is a significant period for hydrocarbon production in the fault layers of the Songliao Basin. Based on the logging data, the thickness of the Shahezi Formation is determined to be 2 624.01 meters （core depth 3 335.99-5 960.00 m）, and the Shahezi Formation is divided into five tertiary sequences SQ1-SQ5 from the bottom to the top. SQ5 sequence has well-developed hydrocarbon source rock, with a high degree of maturity, exhibiting high maturity to over-maturity, characterized by type Ⅲ kerogen. In SQ5 sequence, 35 layers of gas measurement anomalies are detected, with a cumulative thickness of 79 m, and the cumulative thickness of dark mudstone accounted for 59% of the stratigraphic thickness of the sequence, which is the most potential for deep natural gas exploration, followed by SQ2 sequence. Based on the above study, this paper proposes a sedimentary evolution model of the Shahezi Formation, which provides a new vision for the comparative analysis of global marine and land sedimentation. Strengthening the study on evaluating unconventional oil and gas resources of the deep Shahezi Formation of the Songliao Basin is of great significance in leading and demonstrating the expansion of the Songliao Basin’s oil and gas exploration to the deep part of the Basin.