Maintaining and developing the economic strength of any society in the future depends on the performance of the audit committee of that society. Financial expertise is known as the engine of economic and social development of companies. For this reason, methods are used in all countries for individuals and companies to allocate part of their income to voluntary disclosure. The purpose of this research is to investigate the effect of the size of the audit firm and the financial expertise of the audit committee on the voluntary disclosure of banks. The statistical population of the research includes 21 banks admitted to the stock exchange during the years 2014 to 2015. Eviuse software was used to derive the hypotheses. In order to investigate the simultaneous effects of all independent variables on the dependent variable, in addition to the separate regression of each of the independent variables, the overall regression of the variables has also been investigated. The findings show that the first hypothesis, "the size of the audit firm has an insignificant effect on the voluntary disclosure of banks" is confirmed with a value of 3.666. Also, the second hypothesis, "Financial expertise of the audit committee has an insignificant effect on banks' voluntary disclosure" is confirmed with a value of 5.043. These results state that the audit committee and the size of the audit firm are important issues that have always been the concern of corporate investors due to their special role and the impact they have on societies and stock exchange banks.