Objective: The purpose of this study was to investigate the effect of composition and structure of the board of directors and its characteristics on the structure of capital in banks. The spatial domain of this research is the companies accepted in the Tehran Stock Exchange and the domain of the years 2012 to 2017. Methodology: The present research is in applied research. If the classification of types of research based on the nature and method is considered, the method The present research is essentially a descriptive research and is considered as a correlation in the research field. In this research, library method was used to collect data and information. In the research data section, we collected data from sample companies by referring to financial statements, explanatory notes and monthly stock exchange of the Stock Exchange. Based on the systematic elimination method, 134 companies were selected as the statistical sample. Descriptive and inferential statistics were used to describe and explain the collected data. In order to analyze the data, pre-test variance analysis, F lemmer test, Hausman test and Jarck test were used. Then, multivariate regression test was used to confirm and reject the research hypotheses (eviows software). Results: The summary of the research results showed that the ratio of non-executive directors and gender composition of the board of directors does not affect the structure of capital in banks, and the size of the board affects the structure of capital in banks. Conclusion: The financial expertise of the members of the board affects the structure of capital in banks.
