Abstract: Traditional legitimate interests of criminal law are composed of state’s legitimate interest,social legitimate interest and individual legitimate interest,in which the most important duty of criminal law is to protect state's legitimate interest.Under this structure of legitimate interests,scholars often think that criminal law belongs to public law.Although some jurists have put forward that criminal law is the law which guarantees the implementation of other laws many long ago,the opinion that criminal law belongs to public laws is not changed yet,which does not conform to the developing tendency of criminal law.In the view of rule-of-law in criminal,legitimate interests of criminal law should include state’s legitimate interest,social legitimate interest,individual legitimate interest,and ecological legitimate interest.Furthermore,individual legitimate interest is preferential legitimate interest,social legitimate interest and ecological legitimate interest are fundamental legitimate interests,state's legislate interest is guaranteeing legitimate interest.Under this structure of legitimate interests of criminal law,peculiarity of criminal law ought to be defined that criminal law is only the law which guarantees implementation of other laws.This conclusion not only discloses legal peculiarity of criminal law,but also molds legal character of criminal law again.

Key words: criminal law, structure of legal interest, legal peculiarity, guaranty law, legal character