Introduction: The development of effective prevention and intervention programs in preschool period is an essential step in the fight against the obesity epidemic throughout life. The aim of this study was to prioritize the factors affecting the obesity prevention behaviors in 4-6 years old children from the perspective of mothers based on social-cognitive theory. Materials and Methods: This cross-sectional and analytical study was conducted on 240 children aged 4-6 years in Behbahan city, Iran in 2016. The random multi-stage sampling method was used in this study. Data collection tools included a demographic information questionnaire and a questionnaire based on cognitive-social theory (constructs of environment, outcome expectation, emotional coping, self-control and self-efficacy), which its validity and reliability have been evaluated and confirmed (α> 0.7). The questionnaire which was based on cognitive-social theory included 4 obesity prevention behaviors in children (physical activity, consumption of fruits and vegetables, consumption of sugar-free drinks and screen), which were completed by the mothers of these children. SPSS-23 software and Friedman’s test were used to analyze the data. Results: The results of this study suggest that from the mothers' point of view, the constructs of cognitive-social theory affecting obesity prevention behaviors in 4-6 years old children do not have the same priority (p <0.01). Also, considering the mean ratings obtained in this study, the outcome expectation construct in all 4 behaviors of obesity prevention are of primary importance. The average ranking of the outcome expectation construct was 4.38, 4.39, 4.25 and 4.49 in the behaviors of physical activity, consumption of fruits and vegetables, consumption of sugar-free drinks, and the screen, respectively. Conclusion: In designing maternal-centered educational interventions that prevent obesity in 4-6 years old children, the construct of outcome expectation should be given the highest priority. Keywords: Obesity, Pediatric, Lifestyle, Behavior, Health Priorities, Health Planning