The World Customs Organization has issued a number of statements about the provision of strategies to improve the integrity of the world's customs, the most important of which is the "Revised Arusha Declaration". Since the adopters of Arusha Declaration emphasized that the components mentioned in this declaration should be considered according to the conditions of each country and its degree of economic development, this study sought to provide a model for improving the integrity of the Islamic Republic of Iran Customs on the basis of the Arusha Declaration. In order to achieve this model, the Grounded Theory method was used, and the researcher has obtained the required data from the relevant documents (60 items including book, article, research, dissertation) as well as semi-structured interviews from the experts of executive of the customs that have been up to the saturated theoretical (12 people) who have been selected according to the concept of knowledge and purposefully, and after coding and identifying the categories, the model has been presented. Additionally, for model validation, researcher's sensitivity criteria, methodology coherence, sample fit, repetition of a finding, and use of informed feedback were used. The results show that by focusing on three categories of transparency, accountability and regulatory framework and improving the automation, human resource management, relationship with private sector, audit and investigation, organizational risk management, employee efficiency, transparency in codes of conduct, leadership commitment, and promotion of customs procedures can achieve organizational efficiency and improvement of integrity.