Purpose: Psychological well-being is one of the important concepts in positive psychology, which means optimal human performance. This issue has caused researchers around the world to pay attention to the underlying factors of well-being, especially in childhood. The present research was conducted with the aim of designing an integrated model of the underlying factors of psychological wellbeing in children. Materials and methods: This research is descriptive in terms of its purpose and is considered a survey study in terms of data collection. To conduct the research, all the factors related to the issue of psychological well-being in children were identified in the literature by relying on the theoretical foundations and the literature, and further, the validation of the factors was done based on the CVR and CVI tests. The statistical population of the research was the experts in the field of psychology, who especially had studies in the field of children. Purposeful sampling and snowball method were used to select the participants and finally 20 people were considered as a statistical sample. Data analysis was done using fuzzy Delphi method (AHP) and interpretive structural model. Findings: The findings of the research showed that the factors underlying well-being are divided into three dimensions: personal, educational and external, which respectively include factors such as emotional intelligence, personality traits, self-regulation, responsibility, self-efficacy, emotion regulation, perceived social support, mindfulness, and communication patterns., social stress and anxiety for the individual dimension, parent management training, academic performance, positive intelligence training, life skills training and family performance for the educational dimension and finally, parent-child relationship, family cohesion and flexibility, socio-economic status, social networks, parental employment, internet addiction and computer games can be considered as external factors affecting children's psychological well-being. Conclusion: Without a doubt, paying attention to the strengthening aspects of some factors along with the inhibiting aspects of other factors can be effective in improving the psychological well-being of children.