The researchers studied the sedimentary facies of the Yingcheng formation in the Xidingjia area of the Songliao Basin. They used core observations, logging, seismic data, and regional tectonic evolution to analyze the sedimentary facies. The results showed that the area mainly had fan delta, braided river delta, and lake facies, with braided river delta and lacustrine facies being the most common. The sedimentary characteristics indicated a broad shallow basin with fan delta on the southwest steep slope and braided river delta on the northern slope. The sedimentary pattern showed progradation to accretion. This study is important for guiding future exploration and resource evaluation in the area.