Free cash flow is important in that it allows managers to look for opportunities that increase the value of the company's stock. Without having cash, it is not possible to develop new products, conduct business studies, pay cash dividends to shareholders and reduce debts. The purpose of this review is the relationship between transactions with related parties and free cash flow with the moderating role of the auditor's workload. The statistical research population of companies admitted to Tehran Stock Exchange and the studied sample includes 152 admitted companies during the years 1397 to 1401. The research method is descriptive-survey and in terms of the relationship between the variables, it is causal-correlation, and in terms of the purpose, it is applied and in terms of the event, it is post-event. To process and test the hypotheses, the regression method and panel data as well as the fixed effects model have been used. The results obtained from the analysis of hypotheses showed that transactions with related parties have a negative and significant relationship with free cash flow, and auditor workload has a positive and significant effect on the relationship between transactions with related parties and free cash flow.