Defendant retracted is a major problem in our judicial practice. Because the defendant’s pretrial confession lack of constraint of evidence capacity,judges generally finalized on pretrial confession. This is an important cause of miscarriages of justice. Therefore,it is necessary to establish the evidence capacity on the defendant’s pretrial confession. In other countries,there are hearsay exception mode and direct verbal mode on the set of access system,and there are due process mode and arbitrary mode on the set of excluded system. We should draw the direct verbal mode and arbitrary mode.When pretrial confession and trial confession are consistent,the former does not have the evidence capability. When pretrial confession and trial confession are inconsistent,the former can be used as impeachment evidence,and it can also be used as substantial evidence when it has voluntary and arbitrary elements.