In order to understand the paleo-karst cave genesis and fracture-cavity structures in Well TH10421 Block，which has high cumulative production in the thick coverage area of Upper Ordovician in Tahe Oilfield，the distribution characteristics of the surface water system，fracture characteristics，and spatial structure of caves in the area are clarified through paleo-geomorphic restoration，seismic attribute extraction，and fracture-cavity body carving. The fracture-cavity system in Well TH10421 Block is defined as a maze-type cave system caused by flood for the first time. According to the reservoir’s dynamic production characteristics，the connection relationship between fracture-cavity bodies of the maze-type cave system is analyzed. The results suggest that the conjugate secondary strike-slip fault network is developed in Well TH10421 Block，and gridded faults provide an initial dissolution channel for maze-type caves. In episode Ⅱ of the middle Caledonian movement，surface karst lakes provide a high-flow karst water supply， and the karst water infiltrates into Yijianfang Formation along the gridded faults to form maze-type caves. The dissolution of karst water along the faults has the characteristics of simultaneity and selectivity，which results in great differences in the dissolution degree of maze-type caves in Well TH10421 Block in terms of different fault directions and depths. The connectivity of the pipeline in the shallow cave in the east of maze-type caves is excellent，while that in the west of maze-type caves is poor，and the connectivity of the deep fracture-cavity is great.