The purpose of this study was to investigate the effect of internal auditing, supply chain management and knowledge management on total quality management in food manufacturing companies in Tehran province in order to explain the strengths and weaknesses of such manufacturing companies and provide appropriate and practical solutions. To improve their current situation. The present research is based on the applied purpose and based on the nature and method, it is descriptive and in terms of data collection it is survey. The statistical population of the present study consists of all financial managers, auditors, quality control managers and management accountants of companies active in food production companies and food related items in 1399. The validity of the research variables and the resulting indices were examined by LISREL software using the confirmatory factor analysis test, and by using structural equation modeling, which is a mixture of confirmatory factor analysis and path analysis, the hypotheses were tested. The research was conducted. Findings and Results: In connection with the first hypothesis of the research, the results showed that the internal audit variable has a significant effect on quality management. Regarding the second hypothesis, the results showed that the supply chain management variable has a significant effect on quality management. Finally, in connection with the third hypothesis, the results showed that the knowledge management variable has a significant effect on quality management.