Abstract: Through the high precision gravity in Shangdu area,the cognition of basement structure, structure,fault charact eristics,fault distribution,and the distribution of Hannuoba formation basalts has been improved.Shangdu depression has the mono-faulted structural characteristics,that is west-faulting east-overlapping.The sag is north-west trend,which is the components of north-west and south-east secondary sag.There are two northwest-southeast deep-large faults in this area,the faults can be the migration pathway of mantle-derived CO₂,the distribution of CO₂ gas pool is controlled by the faults.The reflection characteristics of basalts of Hannuoba formation is the anomaly of strong magnetism and high density,the basalts can be the good caprock of Xiaodandai formation CO₂ gas pool,which control the distribution of Xiaodandai formation CO₂ gas pool.