Based on relevant theories such as child development, emotional design, and child cognition, the research target is aimed at children aged 3 to 8 years old. The change in the age range of 3-8 years old children from being ignorant to improving their minds is enormous. The application of developmental theory research can better grasp children's demands and characteristics of growth and change. The article designs experiments and uses experimental data to confirm that children of different ages and genders have different needs for colours, shapes, materials, functions, and other aspects. By using experimental methods, one can better grasp the design elements. The experimental evaluation section mainly adopts subjective questionnaire survey method, children's self-rating scale method, semantic difference method, and interview method. On the other hand, organize and analyse experimental data and results.