In traditional Chinese landscape painting, the implicit colors formed by ink wash through variations in density, dryness, wetness, and moisture are the core medium for conveying artistic conception. Taking Mi Youren's "Wonderous Scenery of the Xiao and Xiang Rivers" as a case study, this paper analyzes the technical expression of ink wash colors, the presentation of the painting, and their role in constructing a poetic artistic conception. The study finds that Mi Youren, through techniques such as splashed ink, broken ink, and dotting-dyeing, transformed ink wash into a color language that integrates light-dark layers, spatial rhythm, and emotional warmth. This not only restores the natural characteristics of the mist-shrouded Xiao and Xiang River regions but also conveys spiritual connotations that transcend the material forms of objects. By comparing with the Western realistic view of colors, this paper further reveals the aesthetic value of "governing complexity with simplicity" in traditional Chinese ink wash colors, providing a perspective for understanding the color system of traditional landscape painting.