Due to the reducing number of children and the social transformation of competitive pressures, parents became over-emphasized on pre-school education and negligent in the importance of play. As the proverb goes, ”All work and no play make Jack a dull boy.” Play is a development with an important function of the socialization for children. Parents should take play as a learning medium for children while learning to grow up and adapt to society. Therefore, this study will review the value and significance of the classical theory of play and its importance on children's growing process. The significant influence of modern society on children's mental and social aspects will also be emphasized. Furthermore, we expect to focus on the participation of play and leisure activities by vulnerable children and marginal population in the future, so that each child has fun learning and growing, and enhance future social skills and career development.