The role of the prosecutor's office in non-criminal prosecution is one of the important and challenging issues that require discussion and investigation. The purpose of this article is to examine the role of the prosecutor's office in Iranian law compared to American law.The present article is descriptive and analytical and has investigated the mentioned question by using the library method. The findings indicate that in Iran, the criminal organization has a primary and fundamental role in the stages of crime detection and execution of criminal sentences and is responsible for crime detection and execution of criminal sentences, while in America, crime detection is the responsibility of the police and the prosecutor's office. It oversees compliance with the law in the detection of crimes. In Iran and America, prosecutorial interventions in preliminary investigations have been accepted in different ways. In America, the civil interventions of the prosecutor's office are aimed at carrying out the main tasks, i.e. criminal prosecution. In both legal systems, due to the imposition of numerous tasks outside of criminal prosecution on the prosecutor's office, this institution has faced difficulties in properly performing its main task, which is the management of criminal prosecution, and for this reason, reducing the burden of tasks unrelated to the matter. Prosecution by the prosecutor's office is necessary.