Abstract: The necessity review of detention refers to the judicial activity of the People’s Procuratorate to examine whether there is a need to continue the detention of arrested criminal suspects or defendants in accordance with the provisions of the Criminal Procedure Law. It is of great significance to supervise the whole process of arrest and prevent “arrest bargaining”. In the implementation of this system， there are problems caused by inconsistent legal norms， such as confusion of the subject of the reviewing， non-standard reviewing procedures， and lack of corresponding quantitative basis for judgment. It is urgent to clarify the relationship between relevant legal norms about the necessity review of detention， to restore the mandatory measures of arrest， to improve the supporting systems， and to establish quantitative indicators for the necessity review of detention using the conditions for release on bail and arrest as reference. In addition， attention should also be paid to the number of requests for necessity review of detention and to psychiatric evaluations of detained suspects.

Key words: review of the necessity of detention, arrest, quantitative evaluation, leniency and strictness, judicial fairness