The expansion of the scope of the principle of exclusion of the decision to the stage of preliminary investigation has been one of the most important achievements of modern criminology and one of the bases of changing the legislator's attitude in articles 203 and 286 of the new criminal procedure law. the individualization of preliminary investigations, as a necessary principle and its manifestation in judicial decisions, requires tools, and the creation of a personality file is one of the most basic tools for criminal etiology. it is important to a personality file in the preliminary investigation because the investigating judge, considering the internal, physical, family and social components of the perpetrator, finds out the motivations and causes effective in the occurrence of the crime and issues the best decision according to the personality of the criminal. this research seeks to identify the challenges of using the personality file in preliminary research and its solutions. Therefore, this article, using the analytical-descriptive method and collecting the required information using library studies and relying on the cases in the criminal justice system of Iran, has attempted to enumerate the challenges in the judicial procedure of the prosecutor's office. the result of the research shows that the prosecution and investigation authorities are following the minimal use of the personality file with limitations, the main reasons for which are the attitude and culture that governs them, the lack of training and skills, the lack of proper infrastructure, and the lack of a specific time standard