The Tang Dynasty painted sculptures in the Mogao Grottoes of Dunhuang integrate three-dimensional forms with mineral-based colors, and their visual expressiveness cannot be grasped from a single dimension. Taking the painted sculptures in typical Tang Dynasty caves of the Mogao Grottoes as the research object, this paper systematically analyzes the synergistic mechanism between form and color from four dimensions: lightness contrast and volume shaping, hue temperature and spatial layering, saturation gradient and primary-secondary order, and color rhythm and formal cadence. The study shows that color in these sculptures is not an additional decoration post-sculpting, but a structural element deeply integrated with volume, posture and spatial layout. Together, form and color construct a complete religious narrative and aesthetic order, and their synergistic wisdom offers valuable references for contemporary public art and color design.