This research was conducted with the aim of determining the Effect of transformational leadership on organizational commitment considering the mediating role of teacher satisfaction in secondary school teachers in Tehran in 2019. The methodology of the research applied in terms of purpose and the method of data collection was descriptive-survey. The statistical population of the study included teachers of secondary schools in Tehran, among them, using Cochran's formula and simple random sampling method, 384 people were considered as the sample size. The data collection method was based on organizational commitment, transformational leadership, and job satisfaction Standard questionnaires. After collecting questionnaires, the data were analysed using mean, standard deviation and ... using Spss-21 software and statistical inference of the data through structural equation modelling with the help of LISREL-v8.80 software. The technical characteristics of the questionnaire including reliability, convergent validity and divergent validity were studied. In addition, path coefficients and software significance coefficients were used to examine the research hypotheses. Finally, the findings of the research confirmed the effect of transformational leadership and its dimensions including idealist inspiration, inspirational motivations, stimulation of education and developmental support on the organizational commitment of teachers regarding the mediating role of job satisfaction among secondary school teachers in Tehran.