Abstract: To explore the characteristics of fault structures in the Caspian Sea region, the Bouguer gravity anomaly (BGA) data from the region were systematically processed, based on which a BGA map of the area was produced. In addition, using edge detection technology for potential fields, corresponding edge recognition information was acquired. The Bouguer and residual gravity anomalies were analyzed in detail based on previous geological and geophysical researches, and the regional fault structure framework and tectonic units in the Caspian Sea area were clarified. Results show that the gravity anomalies in the Caspian Sea region exhibit distinct zonation. Bounded by the Nebitdag-Makhachkala-Kizlyar line, the northeastern part of the boundary shows relatively minor macroscopic gravity variations, whereas the western and southern parts of the boundary exhibit more intense changes in gravity field. Based on the regional gravity anomaly features, eight first-order faults (F1–F8) in the Caspian Sea region were recognized. Showing substantial scale and continuity, these faults exert a fundamental control on the tectonic framework of the Caspian Sea region. Five first-order tectonic units were delineated: the Russian Platform, the Ural Fold System, the South Turan Fold System, the Scythian Fold System, and the Tethyan Fold System. This work provided a geological and geophysical support for petroleum exploration in the Caspian Sea region.