The purpose of this study was to explore the effects of theory of mind teaching on the increasing of social-skill behaviors of preschool children with autism spectrum disorder(ASD). The subjects were 13 children with ASD, aged 3-6 years old (M=5; 0), ( IQ ≧ 70), and 13 children with typically development controls (M=4; 9). All subjects were administered the WPPSI-R and the theory-of-mind scale. Parents were in the groups both before and after completing Vineland Adaptive Behavior Scale (VABS). Each subject accepted 10 times the group therapy of theory-of-mind teaching. The obtained data was analyzed by use of descriptive statistics and a t-test. The results showed that theory-of-mind scores for the subjects were significantly lower than controls before therapy. After therapy, the subjects have improved the theory-of-mind scores, and communication, socialization, play skills of VABS.