In recent years, there have been many advances in the Iranian gas company on issues related to safety, health and environment (HSE), but there has not been a proper decision-making structure, and decentralization and reworking have been carried out. The main objective of this study was to investigate the institutionalization of the safety, health and environment culture among the staff of the Tehran Gas Company. The research carried out in this paper is a descriptive-survey research based on the the field research. The statistical population of the research was the staff of the staff of Tehran Gas Company consisting of 775 people. At first, by using the exploratory factor analysis method and through the optimization of the main axes and the rotation of the varimix, dimensions of the HSE culture were identified among the staff of the Tehran Gas Company including eight factors. Then the ranking of HSE culture was computed from the highest to the lowest based on the results of Friedman's analysis: the status of supervisors and managers; the managerial commitment; the staff's ability; the staff's attitude towards the HSE culture; the status of the communication; the status of employee participation; the reporting and priority of safety, health and environment. Finally, by using the T-test, the institutionalization of each dimension of the culture was investigated. The results showed that all of these dimensions were institutionalized, except for the ability of employees in the Tehran Gas Company.