The process by which children depict nature is a wonderful journey from perceptual awareness to artistic expression. This paper aims to explore how children transform the color elements in nature into unique artistic languages based on their cognitive development patterns. By applying children's cognitive psychology, a three-level cognitive model of "sensory reception - thinking processing - memory internalization" is constructed to systematically analyze the complete transformation path from the perception of natural color symbols to the formation of painting languages. The research shows that at the sensory level, children obtain natural symbols through visual, tactile and other sensory channels; at the thinking level, they organize and attribute meanings to the perceived materials by using strategies such as generalization and logic; at the memory level, through the repeated processes of the previous two levels, they construct and form stable painting schemas. The study reveals the intrinsic connection between children's painting expression and cognitive development, providing theoretical basis and practical guidance for children's aesthetic education based on cognitive laws.