Background & Objectives: Schizophrenia is the most severe mental disorder. It not only disrupts the affected person's life and functioning, but also damages the entire family system and disrupts the socialization and growth of life skills. A factor associated with schizophrenia disorder is ego functions, which include Reality testing and object relations; they significantly impact the formation and recurrence of conduct. Reality is among the most critical functions of ego. It is defined as the ability to distinguish the outside world from the inner world and to correctly judge the relationship between the self and the environment. Object relations is the ability of individuals on the representations of themselves and others; it is derived from the child's early relationship with the mother, and this experience affects the individual’ s subsequent relationships. The term representation refers to how individuals cope with that object in their psyche system. Furthermore, it is not the result of the person's exact image, but the residual experience of that person. Determining the mental health conditions of the family system could help prevent relapse in the patients. The healthy family model is useful in achieving such goals; in contrast, the unhealthy family uses destructive family patterns, and their interactions are associated with stress and morbid behavior. Studies on the impact of family environment on schizophrenia highlighted a relationship between disease prognosis, family environment, and relapse rate, as well as the need for readmissions. In pathological approaches, schizophrenia is mainly recognized as a set of symptoms. In these systems, the patient's phenomenal experience is absent, and his/her mental world is limited to a few symptoms. Researchers should, therefore, consider factors related to schizophrenia. Besides, most studies have reported links between Reality testing, object relations, and family functioning. However, modeling the effects of variables on the severity of schizophrenia symptoms has not been discussed precisely. Therefore, the current study aimed to provide a model of the severity of negative symptoms based on object relations and family function with the mediating role of Reality testing. Methods: This was a descriptive and correlational study. The statistical population of this study consisted of 250 patients who referred to 505 Hospitals in Tehran City, Iran, in 2017 and 2018. The study participants were selected using purposive sampling method. Research tools included the Family Functioning Questionnaires (Epstein, Baldwin, and Bishop, 1983), the Object Relations Scale (Bell, 1995), the Reality testing Scale (Bell, 1995), and the Positive and Negative Syndrome Scale (PANSS) (Kay, Fizbin, & Oppler, 1986). Pearson correlation method and structural equation modeling were used to analyze the obtained data in SPSS and LISREL. Results: Pearson correlation data revealed a positive and significant correlation between object relations, Reality testing, and the severity of negative symptoms (p<0. 001). Moreover, there was a positive and significant association between object relations, family functioning, and the severity of negative symptoms (p<0. 001). However, there was a significant and negative relationship between family functioning, Reality testing, and the severity of negative symptoms (p<0. 001). The structural modeling of path analysis results demonstrated that the object relation and family function, with the mediating role of Reality, could explain the severity of negative symptoms in the affected patients (p<0. 001). Conclusion: The current study findings indicated that object relations and family function with the mediating role of Reality testing could be an appropriate model for predicting the severity of negative symptoms of schizophrenia.