As a special type of illustration, illustration design in children's books can transmit aesthetic education ideas to children with vivid and interesting narrative pictures, enriching children's cognition, helping them establish good emotional attitudes and values, and finally building a complete personality. In recent years, the rise of the Chinese children's book market and the emphasis of education on children's aesthetic education make the concept of aesthetic education play a more and more important role in the illustration design of children's books. The work aims to discuss the importance of aesthetic education in the creativity and expression of illustration design of children's books from the perspectives of education, children's aesthetic psychology and design science. Through the methods of interdisciplinary research, literature research, case analysis, combined with the horizontal comparative analysis of Robert Piaget's theory of cognitive development stages and Howard Gardner's theory of children's aesthetic cognitive development stages, the children's illustration preferences at different stages were exported. On the basis of understanding the developmental characteristics of children's aesthetic psychology at different stages, the important role of aesthetic education in the illustration of children's books was discussed. It is hoped that art creators should pay more attention to children's aesthetic education, correctly guide the direction of illustration design of children's books, strengthen the cultivation of children's aesthetic ability, and better transmit Chinese culture and tell Chinese stories well from the field of design.