Abstract: Using coal gangue powder alone as reclaimed soil in mining areas presents issues such as low porosity and poor water retention. To enhance the water retention capacity of coal gangue powder, a cost−effective porous material with rich pore structure was developed using coal gangue as the raw material. This study investigated the effects of adding varying proportions of coal gangue−based porous material to coal gangue powder on its water retention capacity and pore characteristics. Coal gangue powder was mixed with the coal gangue−based porous materials at volume ratios of 10∶0, 9∶1, 8∶2, 7.5∶2.5, and 7∶3. The soil water retention curves under different treatments were determined using the centrifugation method and fitted with three empirical models including Brooks−Corey (BC) model, van Genuchten (VG) model, and Gardner (G) model. The applicability and fitting accuracy of these models were analyzed. The variations in bulk density and shrinkage with soil water suction during the measurement of water retention curves were also elucidated. Both the BC model and VG model effectively describe the soil water retention curves for different mixing ratios of the coal gangue−based porous materials and coal gangue powder. The addition of this porous material can reduce the bulk density of coal gangue powder and increase its saturated water content and field water holding capacity. The addition of 25% coal gangue−based porous materials into coal gangue powder increases the effective water content by 2.90% and enhance the total porosity by 19.24%. The addition shows no notable impact on the shrinkage of coal gangue powder, indicating the inherent stability of the coal gangue powder. The optimal mixing ratio of coal gangue−based porous materials to coal gangue powder is determined to be 2.5∶7.5 (volume ratio), which effectively enhances the water retention performance of coal gangue powder. Applying this porous material for topsoil reconstruction in ecological restoration can prevent secondary land degradation, conserve natural loess resources, recycle solid waste, reduce environmental pollution, and hold significant practical value for vegetation restoration in mining areas.