This study deals with how the korean open treatment for prisoners, especially the classification of prisoners and the progressive stage system in the 21st century should be implemented effectively. For this study, the historical trace of criminal policy theories and the correctional policies in korea and the open treatment system in some other advanced countries were reviewed. The classification of prisoners and the progressive stage system(so-called horizontal classification and vertical classification) such as open facilities, has been extensively used in the developed countries and it has been generally successful in rehabilitating inmates effectively. Today, in our society, serious concern about protection from crimes and the revision of existing penal system are demanded. At the same time, The direction of revising the Law of Criminal Punishment Execution should consider the very idea of the Constitution. In concrete, the management classification and the treatment classification such as individualized treatment should be protected in the name of their basic rights which are guaranteed in the Constitution. Many revisions should be done in the law of criminal punishment execution in a way that the law protects inmates' basic rights.