Color is the primary expressive language of watercolor art, with the interplay of "water" and "color" forming its soul. Located in the Lingnan region, Guangdong has developed a unique artistic style in watercolor techniques and color language due to its distinctive climate, profound cultural heritage, and open, inclusive humanistic characteristics. This study systematically examines the intrinsic principles of the interaction between "water" and "color" in Guangdong watercolor paintings, analyzing the distinctive aesthetic connotations of their harmonious interplay. From the color blending in wet-on-wet techniques, precise layering under controlled water application, to the texture generation in water mark shaping and the color expansion achieved through mixed media integration, the paper traces the evolution of Guangdong watercolor's color language from experiential summarization to standardized construction through the works of veteran artists such as Chen Haining and Huang Zengyan, as well as emerging talents like Liang Guohui and Su Junquan. Research confirms that the interplay of watercolor techniques and color language not only establishes a solid foundation for the aesthetic system of Guangdong watercolor but also serves as a vital expressive form that embodies regional characteristics and carries the spirit of the times, giving rise to the distinctive "Guangdong School of Watercolor.