The Permian Maokou Formation in the Yunjin Syncline, southeastern Sichuan Basin Province, has developed limestone reservoirs. With the development of oil and gas exploration, the exploration direction has gradually expanded from the high part of the structure to the syncline area, in recent years, wells such as H7, YJ2 and H207 in Yunjin syncline area have been breaking through continuously. The matrix of the limestone reservoir is relatively poor, and the reservoir-forming conditions can only be obtained under the transformation of the solution pores, cavities and fractures formed by karstification, which also leads to the strong heterogeneity of the reservoir, the diversity of types and the complexity of seismic response characteristics, reservoir prediction is difficult. Firstly, by establishing the logging identification standard of different reservoir types, using the cast thin section, core photograph and imaging logging data analysis, the reservoir types are classified, and the conventional logging response characteristics of different reservoir types are defined, the reservoir types of Maokou Formation can be divided into fracture type, fracture-vuggy type and matrix pore type. On the basis of log identification, the “Three-definite identification flow” of karst fracture-cave reservoir is established by using high-resolution seismic data The threshold value of fracture zone boundary is determined by using chaotic volume, structural tensor and seismic discontinuity, and the reservoir boundary is determined by using electrical imaging and conventional logging data. On this basis, the reservoir is further realized by the methods of seismic forward, Karst palaeogeomorphology and reservoir inversion, which ensures the accuracy and reliability of reservoir prediction.