As the core visual language of oil painting art, color serves as a crucial carrier for painters to convey emotions, construct artistic conception and express thoughts. Since the birth of oil painting, the application of color has been constantly evolving with the changes of artistic trends and the advancement of painting techniques, forming distinctive color styles and expression systems. Taking the application of color in oil painting as the core research object, this paper analyzes it from three dimensions: the emotional expression function, the spatial shaping value and the theme sublimation effect of color. Combined with the classic works of representative painters in different periods such as the Renaissance, Impressionism and Expressionism, this paper deeply explores the rules and innovative paths of color application. Meanwhile, through the interpretation of techniques such as color matching, tone control and color contrast in specific works, it reveals the key role of color in enhancing the artistic appeal of oil paintings and improving the artistic value of works, so as to provide theoretical reference and practical reference for the application of color in contemporary oil painting creation.