Abstract: Coal beds occur in a wide area and developed with big thickness in south slope of Huimin Sag.These coal beds are sediments of marine-terrestrial interface which deposited under environments of tidal flat and lagoon.It is shown by gas generation simulation experiments that the gas generation potential of the Taiyuan and Shanxi Formation are 150mL/g and 1 10mL/g organic matter respectively.The source rock of coal-formed gas has a very complex thermal evolution process.The second gas generation occurred from the Early Tertiary to the Quaternary, with a threshold tempreture of 135℃ and corresponding depth of 4000m..The effective gas generation center is located in eastern of the Jiyang Graben and Quti Horst.The gas generation intensity is about 20 ×10 8m3／km2 to 40 ×10 8m3／km. Therefore,eastern parts of Quti Horst is the main target of exploration.