Color construction in watercolor practice often remains at an experiential level, making it difficult to establish transferable teaching pathways and stable creative judgment. In practice, the drifting of the dominant tone, imbalance in value structure, and the accumulation of disordered contrasts can fragment the overall value system, leading to weakened spatial hierarchy and disoriented viewing paths.This study takes “color decision-making” as its entry point and constructs a logical chain from dominant tone selection to value coordination. Through comparative analysis of the author’s works within the same tonal system, it summarizes shared principles in value structuring and chroma range positioning. The effectiveness of this framework is verified in stabilizing spatial relationships, maintaining tonal unity, and enhancing atmospheric controllability, thereby providing a reproducible decision-making approach for both teaching and creative practice.