Abstract: Paleokarst underground rivers are extensively developed in the Ordovician carbonate reservoirs of Tahe Oilfield. Their large burial depth and complex morphology make it challenging to accurately delineate their spatial distribution. This study employs forward modeling, multi-attribute stacking, well log interpretation, and drilling validation to quantitatively characterize the width and height of these underground rivers. Based on forward modeling and quantitative analysis of different cavern widths, correction templates are developed. Hierarchical river width correction is then achieved using multi-attribute stacking. To quantitatively characterize river height within its boundaries, the frequency attenuation gradient attribute is extracted from time-frequency analysis of poststack seismic data to establish a fitting relationship with the log-interpreted height of actual drilled rivers. This methodology is applied to the Tarim Basin, effectively converting seismic anomaly scale to geological scale for paleokarst underground rivers, thereby providing a technical foundation for the efficient development of fracture-cavity reservoirs associated with such rivers. Drilling validation shows that post-correction accuracy reaches 90% for rivers wider than 100 m and approximately 80% for those 50–100 m wide, while reliability is low for rivers narrower than 50 m. Well-to-seismic calibration reveals a strong linear correlation (R² ≈ 0.80) between the high-frequency attenuation gradient and river height, confirming the effectiveness of this attribute for quantitative characterization. Hierarchical correction is integrated with frequency gradient attribute for quantitative characterization of river width and height. This integrated approach offers a valuable reference for similar regions.