The purpose of this study is to investigate the effect of board diversity on firm risk-taking by explaining the moderating role of the effects of board independence, CEO duality and free cash flows in companies listed on the Tehran Stock Exchange, along with practical suggestions. The present research is applied research in terms of purpose. This research is of descriptive correlation type and research methodology is post-event type. To test the hypotheses, a multivariate regression model was used. The data obtained in relation to the research variables were entered into an Excel spreadsheet and then analyzed using EViews and Stata software. The statistical population of this research is the systematic elimination method from all companies listed on the Tehran Stock Exchange during the period 1390 to 1398. The results of the first hypothesis of the research showed that the diversity of the board of directors has a significant effect on the company's risk-taking. The results of the second hypothesis indicate that the independence of the board of directors has a significant effect on the relationship between the diversity of the board of directors and the company's risk-taking. The findings of the third hypothesis also show that board duality has a significant effect on the relationship between board diversity and firm risk-taking. Finally, the findings of the fourth hypothesis show that free cash flow has no significant effect on the relationship between board diversity and firm risk-taking.