Abstract: This research aims at analyzing the relationship between the geothermal evolution of Permian source rocks and hydrocarbon generation in Ejin Banner and its vicinities. Based on the information of vitrinite reflectance, temperature data of liquid-phase inclusions and apatite fission tracks, the authors measured the paleogeothermal gradient of Ejin Banner area when it reached maximum gradient. Based on an analysis of the geothermal evolution history of Ejin Banner area, the authors investigated the relationship between the geothermal evolution and hydrocarbon generation. The results indicate that Ejin Banner area reached maximum gradient in Cretaceous period, with the paleogeothermal gradient being 4.1～5.5℃/100m. A comparison with the neighboring Chagan sag has revealed that the paleogeothermal gradient of Ejin Banner area was higher than its modern geothermal gradient. The Permian source rock geothermal evolution was mainly controlled by the paleogeothermal field. The research on the relationship between the geothermal evolution history and hydrocarbon generation indicates that some parts of Ejin Banner area entered into the hydrocarbon generation period in Late Permian. During the hydrocarbon-forming phase, the dry gas was dominant. In the Early Cretaceous period, the geothermal evolution of this area reached its maximum level.