The Chishui Danxia landform in China is characterized by bright red-bed sandstone, yet the quantitative factors controlling its color diversity remain insufficiently understood. The study was aimed to investigate the mechanisms of sandstone color variation under environmental influences to support color matching in ecological restoration. A multidimensional sampling strategy, including planar-vertical isolation and single-factor control, was applied. Color parameters were measured using the CIE-Lab system. Mineral compositions were analyzed by X-ray diffraction(XRD) and scanning electron microscope-energy dispersive spectrometer(SEM-EDS), and iron speciation was determined spectrophotometrically. The results of material composition analysis indicate that hematite and clay minerals dominate the red tone of sandstone through the coloring effect and adsorption of Fe³⁺, respectively. The valence state of Fe element further changes the color characteristics of sandstone with depth. Microstructural analysis shows that sandstone in strongly weathered zones exhibits a looser fabric and more fractured grains. The parameter b of Lab color space has increased by 5.91 compared with weakly weathered zones, corresponding to a brighter surface appearance. A temperature increase of 10 ℃ decreases the b by 0.38, while moisture affects brightness through variations in the parameter L of Lab color space. Controlled experiments confirm these environmental effects. This study establishes a quantitative framework linking mineral composition, microstructural evolution, and environmental factors to color expression, providing a scientific basis for color-compatible restoration materials in Danxia landscapes.