Under the macro background of the reform of procuratorial institutions and the adjustment of functions，in the face of the current situation of poor procuratorial supervision，it is important to understand the importance of procuratorial supervision，especially the pre-trial procuratorial supervision，from the theoretical and practical aspects，and respond to the “integration of arrest and proceeding”.This paper puts forward some preliminary ideas for the pre-trial procuratorial supervision of China's reform，focusing on the prosecutorial supervision of the verification of the legality of interrogation before the end of the investigation. We will change the situation of post-supervision supervision and effectiveness，promote the simultaneous “procedural” pre-trial inspection and supervision，establish a participatory procuratorial supervision system，use the procurator's rotation to station the detention center，combine supervision and accountability，and establish a rigid supervision system.