According to the first paragraph of Article 16 of the General Principles of the Civil Law, "the parents of minors are their guardians." That is to say, for minors, their parents are their legal guardians. Both parents have equal custody of their children, and no one shall be deprived or restricted except for death, legal termination of the relationship between parents and children, or deprivation of custody according to law. Therefore, both parents have the right of guardianship and the obligation of guardianship for their children, whether divorced or not. After being appointed, the guardian shall not be changed. In case of unauthorized change, the original designated guardian and the changed guardian shall bear the guardianship responsibility. After the divorce of husband and wife, there are three situations for the change of child custody:
 1、 The existing guardian has lost the ability to supervise
 2、 The guardian does not perform the right of guardianship, that is, the guardian has the ability but does not perform the duty of guardianship
 3、 Due to the loss of guardian.