Background and Objective: Children with Autism spectrum Disorder (ASD) are limited in participation in everyday activities due to the nature of their disorder. Participation means involvement in life situations. The aim of this study was to evaluate psychometric properties of "the Children Participation Assessment Scale-Parent Version" (CPAS-P) in activities outside of school in Iranian children with ASD. Material and Methods: The sample consisted of 55 parents of 6-12 years old children with ASD who selected with convenience sampling. For assessing the convergent validity of CPAS-P and Vinland Adaptive Behavior Scale (VABS), the spearman's correlation coefficient test was used. The internal consistency and test-retest reliability were determined by using the Cronbach's alpha and the intraclass correlation coefficient (ICC), respectively. Results: The mean age of children was 7.62 years. Cronbach's alpha was obtained 0.91 to 0.94, which indicates the proper internal consistency and ICC was 0.90 to 0.95, which indicates the acceptable test-retest reliability. Finally, significant correlations were reported between CPAS-P and VABS tests in related subscales. Conclusion: Increasing independence in doing daily activities of children with ASD is a concern for rehabilitation professions such as occupational therapists. Valid and reliable instruments are necessary for documenting treatment that should culturally adapted among Iranian children. According to the result of this study, CPAS-P has good psychometric properties for clinical practice and research.