Internal audit is used to improve compliance with laws, quality of financial reporting and synergy of municipal operations. Due to its role in improving internal controls and risk management along with providing advice to managers, internal audit is considered one of the important issues of corporate governance and organizational competence. This issue is more important in citizen-oriented organizations such as municipalities. The purpose of this research is to identify the weak points of the internal audit of municipalities based on the study of specialized texts and asking experts' opinions. For this purpose, specialized texts were studied and opinions were sought from 14 expert experts who were familiar with the subject of Internal audit and activities of municipalities, and after performing mathematical and fuzzy calculations, 20 main weaknesses and 217 secondary weaknesses were identified. All components were accepted in the phase of fuzzy Delphi with a score above 70%. Among these, the most important components with an acceptance score above 90% were: Weakness of the economic environment, weakness of service compensation, weakness of independence, weakness of institutionalization, weakness of leadership, weakness of the structure of reporting lines, weakness of promotion, weakness of the legal environment, weakness of effectiveness, weakness of distrust and weakness of management mechanisms. The importance of the economic environment due to high economic fluctuations and the importance of compensation refers to the correct managers of human resources. Internal audit in municipalities should be given serious attention and long-term, medium-term and short-term plans should be designed to eliminate weak points. Considering the sensitivity of municipalities' duties, this research has value for improving the monitoring and risk management of municipalities.