Today, the challenges facing organizations are more complex. The excellence level of systems thinking (ST) in an organization indicates the organization's ability to overcome these issues. This study aims to present an excellence model for assessing the level of ST in organizations. First, according to the systematic review process of documents related to ST and assessing ST, 39 documents have been verified in terms of quality and, by using the Critical Appraisal Skills Programme (CASP), the final documents were selected. Then, by three-stage coding of selected documents, codes, concepts and categories were identified. Based on the outputs of coding stage and placing the 2020 model of EFQM, the dimensions, criteria and sub-criteria for evaluation of ST in the organization were defined and organizational systems thinking excellence model (OSTEM) was developed. To evaluate the validity of the designed model, the content validity index (CVI) was used. The final model includes three sections: direction, execution and results.