###### Abstract  
Accurate prediction of the water-bearing capacity of aquifers is crucial for protecting the surface ecological environment and ensuring safety during coal mining. In this study, a macro-micro combination was used to investigate the water-bearing capacity of bedrock aquifers. At the micro-level, the micro pore parameters of various sandstones were determined through cast sheeting. At the macro-level, the porosity and water absorption rate of various sandstones were determined experimentally. After that, a new index weighting method was proposed to comprehensively evaluate the water-bearing capacity index of sandstone. According to this method, the water-bearing capacity of aquifers in the Guojahie coalmine were evaluated. The research results revealed that the water-bearing capacity of sandstone was mainly related to its pore connectivity, and the water-bearing capacity of sandstone in the Luo'he and Zhi'luo formation was considerably greater than that in the Yan'an formation. The water bearing capacity of strata in the eastern part of the mining area is lower than that in the western part of the mining area. The research results can provide considerable money savings for coal mining and protect the ecological environment and groundwater resources in the region. p 2021 14 4865 15 July 2021 6 August 2021 99 August 2021 999 10.10.  
of various technologies, including low field nuclear magnetic resonance (LF-NMR) [20], nuclear magnetic resonance (NMR) and mercury intrusion porosimetry (MIP) [21], \(X\)-ray diffraction (XRD) analysis, thin section, scanning electron microscopy (SEM) [22], small Angle neutron scattering (SANS) [23], X-ray computed tomography (XCT) [24; 25], low temperature nitrogen adsorption (LTNA), rate-controlled mercury intrusion (RCOII) and high pressure mercury intrusion (HPMI) [26; 27]. These experiments provide advanced methods for the study of the microscopic pore structure of sandstone. However, few scholars pay attention to the effect of pore structure on the water-bearing capacity of sandstone in the field of water control in coal mining. Therefore, based on previous studies, this study considered the Guojiahe coal mine as an example. Sandstone-type water-bearing capacity has been comprehensively analyzed from the micro and macro perspectives. On the micro level, the plane porosity (PP), average pore diameter (APD), average specific surface (ASS), pore sorting coefficient (PSC), and throat homogenization coefficient (THC) of sandstone with various lithologies are determined through cast sheeting. On the macro level, the porosity and natural water absorption of various sandstone types are obtained by measuring pressure porosity and rock natural water absorption (NWA). Through exploratory data analysis (EDA) of the indexes, it was found that there is a strong correlation between the indicators. Therefore, this paper proposes a new index weighting method that may well identify factors affecting the water-bearing capacity of sandstone formations. Grey relational analysis (GRA) method may be effective for evaluating the correlation between indicators and ranking different indicators according to their importance, but it cannot accurately provide quantitative weight assignment [28; 29; 30]. The new method considers the basis of the grey correlation coefficient, quantitatively estimates the change trend between sequences, considers the analysis of the nonlinear relation between multiple variables which is used to determine the grey correlation coefficient, and then establishes an objective evaluation based on the grey correlation coefficient matrix and computing feature vector according to different characteristics of the matrix vector value of sensitivity calculation [31; 32; 33; 34]. On this basis, the model of sandstone water capacity is established.