The potential of oil and gas exploration and development in buried hill reservoir is huge, but the spatial and temporal distribution of fractures has strong complexity and non-uniformity, and accurate prediction of fracture characterization parameters is crucial for all aspects of the whole life cycle of oil and gas exploration and development. To this end, a coupled geomechanical model is established based on multivariate geologic data to invert the distribution of the stress field during the active period of each tectonic movement in the buried hill reservoir in the Bohai Sea, for example. Based on the theory that cracks are generated in the active period of multi-phase tectonic movement, the superposition analysis of crack parameters in multi-phase tectonic stress field is carried out to realize the quantitative prediction of characteristic parameters of cracks in the buried hill reservoir of the Bohai Sea block, and the accuracy of the prediction results of crack openings and densities is verified by core description and imaging logging. The results show that reservoir fracture development is jointly influenced by folds and faults, and the high fracture line density areas are mainly concentrated in folds, faults and their combination with nearby strata; the fracture openings in the dorsal axial part are higher than those in the flanks, and the openings in the areas where faults are combined with the surrounding strata are lower; and the predicted fracture density and fracture openings have an error of 11.74% and 9.69%, respectively. The results of the study provide a new idea for quantitative prediction of the characteristic parameters of cracks in the buried hill reservoir, and provide geological basis and engineering guidance for rational exploration and development of the buried hill reservoir.