Abstract: The improvement of the leniency policy for guilty plea and punishment acceptance is the institutionalization of criminal policy of combining punishment with leniency and the innovation of criminal prosecution procedure. For a long time, the leniency policy for guilty plea and punishment acceptance has been inadequate in entity and procedure, so we should improve it. Borrowing from American plea bargaining system and taking our current situation of rule by law and judicial environment into consideration, this thesis attempts to improve the "negotiable" leniency policy for guilty plea and punishment acceptance.