The realization of the concept of criminal justice requires guaranteeing the rights of individuals and determining the guarantee of practical and decisive implementation against the violation of fair trial standards. Fair trial means the general guarantees that are provided in the judicial mechanism to respect the rights of the parties in the trial process of all kinds of lawsuits before a competent, independent, impartial court. Therefore, the implementation of fair proceedings within the framework of the laws prevents the generalization of unfair and arbitrary examples. The research aims to explain the issue of fair proceedings in Iranian and French laws by descriptive-analytical method, and aims to compare examples of fair proceedings and in this way promote fair proceedings. As a result, experience has shown that the rights of the accused are more vulnerable at this stage compared to other stages of criminal proceedings, and French law can be used to eliminate the gaps in Iran's criminal law. In addition, the examination of Iranian and French law shows the commonality of the concept of fair trial; However, in the realization of some examples and the way they are used, such as using a lawyer in the proceedings, they have a semantic difference with each other.