<p>The reconstructed dump stratigraphy resulting from open-pit mining exhibits significant spatial heterogeneity, which deeply affects geotechnical stability and ecological restoration processes. Existing studies have primarily focused on particle-size distribution at the bench scale, with limited attention to the spatial heterogeneity of geomaterial distribution at the overall dump scale. Based on high-resolution UAV remote sensing imagery, this study proposes a method for precise monitoring and quantitative evaluation of spatial heterogeneity in geomaterial distribution within reconstructed dump stratigraphy. By constructing a Stratigraphic Similarity Index (SSI) and a Geological Homogeneity Index (GHI), the spatial characteristics of geomaterial distribution are quantitatively characterized from two perspectives: vertical stratigraphic structural similarity and within-layer homogeneity. Using the Haerwusu Open-Pit Coal Mine as a case study, the results show that the average SSI across 30 evaluation units is 0.48, indicating that approximately 50% of the original vertical structural characteristics of the geomaterial distribution were retained during reconstruction. The GHI values range from 0.07 to 1.00, showing a decreasing trend with elevation, and the GHI coefficient of variation exceeds 0.30 in about 70% of the evaluation units, suggesting significant differences in geomaterial distribution across stratigraphic levels. The combined analysis of SSI and GHI further reveals that open-pit mining induces significant vertical differentiation in the disturbance of the original geomaterial distribution, with the basal stratigraphy being less disturbed and retaining a higher degree of its original structure. The proposed method provides a theoretical foundation and methodological support for zoned geological hazard prevention and targeted ecological restoration in mining areas.</p>