OBJECTIVE: This study used a randomized controlled trial to report the long-term effects of intensive social training in preschool children with autism at 12 months. METHODS: Sixty-one children with autism (of whom, 48 were boys), aged 29 months to 60 months, were randomly assigned to two groups. One group underwent 8 weeks of pre-normative chemistry training with intensive pre-socialization training (n = 34), and the control group underwent pre-normative chemistry training only (n = 27). While in previous studies, intensive social skills training has been found to have a facilitative effect on short-term interventions for children with autism, the present study looked at examining long-term effects. In the study, the experimenter assessed social, language, overall social functioning, and communication aspects, respectively, through pre-school video screens of teacher-child and mother-child interactions, the Early Social Communication Scale, the Neynell Assessment of Language Development, and the Social Communication Questionnaire. RESULTS: After the 8 weeks of training, a return visit for effects was conducted at 12 months. It was found that children in the treatment group were found to have more significant improvements in both joint attention and joint participation at long-term follow-up through a short-term (8-week) intensive social skills training based on normative training compared to children in the control group; however, the 8-week training did not produce significant long-term efficacy in terms of non-verbal IQ and expressive language levels for both groups. CONCLUSION: This suggests that even short-term intensive training of social skills in preschool children with autism still has a more lasting effect on later social communication skills. Of interest, improvements in social skills such as joint attention and active engagement appeared early and preceded the overall improvement in expressive language skills and communication skills. More research is needed to clarify whether it is possible to further improve treatment effects by increasing the intensity and duration of social training.