Due to the fact that after receiving the visual stimulus, the cerebrum will direct the body to make a response to the information, therefore, it is an important factor for the young children to develop the cerebrum through vision to learn new knowledge. It can not only touch off children’s imagination, but also can promote children’s concentration. The reason why visual illusion is created is due to that people is cheated by the existing cognition of the cerebrum and the vision of eyes. And colour, view angle, distance, etc. all can cause the difference between vision and reality. Nobody can deny the importance of vision, because not only the simple behaviour but also complicated cognition are depend on the vision’s assistance. This study aims to explore the application of visual illusion on children’s toy design and to understand the effect of it. It hopes to be able to enlighten designers and thus can combine the incredible visual illusion into children’s toy design to create more fun and attractive toys. The results reveal that applying visual illusion on children’s toy design has effects on children’s preference on toys. In addition, participants can perceive the phenomena of the part of the testing visual illusion figures and there is no significant difference between male and female young children.