Purpose and Background: Designing an appropriate organizational structure is very crucial in determining organizational performance. Organizational structure by itself does not lead to success, but the weak structure makes successful performance impossible. On this basis, designing a new optimal model of the organizational structure for the Deputy of Rehabilitation of the Welfare Organization is considered. Research Method: This research is conducted in three stages. In the first stage that is performed qualitatively, the data is collected through conducting structured interviews with rehabilitation authorities, managers, and experts. In the second stage, the key themes are extracted and are converted to the corresponding model. In the last stage, testing the extracted model is also performed, and this stage is conducted quantitatively. Findings: Based on the results, the factors identified in the foundation data model were influential on each other. The factor load of causal factors on the main category was 0.71, and its t-statistic was 5.67. The factor load of the contextual factors on the strategies was 0.52 and its t-statistic was 3.61. The factor load of the intervening factors on the strategies was 0.44 and its t-statistic was 2.59. The factor load of the main category on the strategies was 0.68 and its t-statistic was 4.7. Finally, the factor load of the strategies on the consequences was 0.69, and its t-statistic was 8.24. Conclusion: In general, concerning all indicators, the model had a good fit. Factor loads indicated the impact ratio of the observed variable in explaining and measuring the hidden variables related to it. On this basis, it can be said that designing the new optimal model of the organizational structure of the Deputy of Rehabilitation of the Welfare Organization has been done appropriately.