Abstract: The present process of our criminal judicial investigation requires relatives' "mutual certification", which goes against the deep-rooted tradition to accord the topmost priorities to family bond and human relations. In view of this, this essay proposes that the Criminal Procedure Law should draw on the legal thinking of relatives' "mutual concealment" in ancient China and the similar stipulation in foreign legislation to reconstruct the legal system of relatives' "mutual concealment" by defining the nature of "the concealment rights of relatives", the scope of the subject of close relatives and the application of restricted crimes, etc.