The advantage of lawyers' involvement in criminal cases at this time is that the investigation organ is in a relative control position when interrogating criminal suspects or after taking compulsory measures. From the perspective of checking and balancing the exercise of investigation power of investigation organs, criminal suspects need professionals to provide them with legal services. Although a criminal suspect is suspected of committing a crime, his personal rights, property rights and other legitimate rights and interests are still protected by law. Lawyers' intervention in accordance with the law can effectively avoid acts that infringe on the legitimate rights and interests of criminal suspects, such as extorting confessions by torture.