Abstract: This comparative study on the social and cognitive complexity in play among 150 Chinese and American children had been made based on time-sampling observation video-tape. The results indicated.:1.The level of social and cognitive development of preschoolers advanced with age.2.There was a correlation between the higher level cognitive play behavior and the higher level of development of social skills,both of them influenced each other.3.There was a coincidence in the progress of social and cognitive ability between the children from both countries as well as in the developmental modes of the play behavior.4. There was a difference in the forms and contents of the preschoolers, play, in the social and cognitive level between the children from both countries, which showed the influence of different cultural backgrounds.

Key words: Chinese and American preschoolers, play, social type, cognitive type, cross-cultural comparison