The Criminal Procedure Law stipulates that:
Source Shantou lawyer web page link
Article 83, paragraph 2: Immediately after detention, the detained person shall be sent to the detention center for detention, which shall not exceed 24 hours at the latest. Unless it is impossible to notify or the notification of suspected crimes endangering national security or terrorist activities may hinder the investigation, the family members of the detained person shall be notified within 24 hours after detention. After the circumstances that hinder the investigation disappear, the family members of the detained person shall be notified immediately.