This paper reviews studies on the origin of \'theory of mind\' in infancy and children with autism. The development of social understanding has been one of major concerns under the heading of children\'s theories of mind. Researchs on social understanding, from this perspective, focused initially on the preschool period. However, it was pointed out that even in the first year, infants show a good deal of social sensitivity, which resulted many theoretical concerns of \'the origins of theory of mind\'. Leslie\'s theory of mind mechanism, Baron-Cohen\'s mind-reading system and Meltzoff\'s imitation theory were the hypotheses of the origins of theory of mind. Imitation has developmental and social value. Imitation of others\' behavior and facial expression is the sign of understanding self and others. Many empirical studies suggested that children with autism show deficits in imitation, which might influence their social development. In conclusion, teaching the imitation skills to children with autism might positive influence on their understanding others.