Natural environmental color is a core element of regional visual identity. Scientifically extracting and quantifying it is of great significance for cultural heritage preservation, regional image building, and design innovation. This study, taking the unique natural landscape of Dongchuan Red Earth in Yunnan as a case study, employs a color geography research paradigm and combines field sampling with digital tools to systematically explore the composition and seasonal evolution of its environmental color. The results show that the color system of Dongchuan Red Earth has a strong seasonal identity. Its color composition is not only derived from the inherent red color of the soil but is also dynamically influenced by environmental factors such as crop rotation, sky illumination, and distant mountain vegetation. This study develops a method for translating natural environments into applicable color schemes. The results can provide precise, scientific data support and aesthetic basis for color strategies in environmental design, visual communication, and cultural tourism products.