Abstract: Metamorphic core complex was discovered in the Changling Faulted Depression of Songliao Basin. This metamorphic core complex has a typical three-layer configuration, including the metamorphic core, the unmetamorphosed cover and the ductile shear belt. It uplifted during the Yingcheng period in the Early Cretaceous, caused by magmatic emplacement and large-scale extensional detachment. After the orogeny in the Late Jurassic, the orogen extension and collapse and mountain root delamination since the Early Cretaceous resulted in strong crustal thinning and large-scale extensional detachment. At the same time the faulted depression group and metamorphic core complex were formed in the Songliao Basin. The impact of the metamorphic core complex on oil and gas were discussed, suggesting that the metamorphic core complex has an important influence on hydrocarbon accumulation of the Longfengshan Oil-and-Gas Field, which shows good potential for oil and gas exploration.