The main challenge of the corporate governance system of banks is the need for a superior auditing system to perform the integrated auditing expected of all stakeholders and supervisors, considering the maturity, risk, Coso and Basel Committee in this study, called composite auditing. From this research, the explanation of the Critical effective factors of audit success, internal banking and audit approach (MRCB). This research is descriptive-survey in terms of type and applied-developmental goal and in terms of contextual-exploratory method. Research data collection method includes library, interview and field method and statistical population including banks and financial and credit institutions and sample population including, community of experts 16 people and sample population 62 people through Classification-random statistical sampling between experts, supervisors, managers, auditors and statutory auditors of banks. Research stages include,A theoretical study with Delphi method in three rounds and a quantitative research with Bernoulli distribution test, Chi-square, factor analysis and Friedman. The research findings lead to the explanation of the critical effective factors for the success of internal audit of banks in the internal and external dimensions of the organization, in four sections: environmental factors, including,Strength 17, weakness 16, opportunity 21 and threat 17 factors, which according to these factors with unique characteristics of organizational dimensions can meet the expectations of all stakeholders and banking supervisors and lead to the internal audit of banks and for future research in the field. The excellence of the internal audit profession will be useful in Iran and the world