If both parties have children, the ownership of the child custody must be clearly stated in the divorce agreement. Otherwise, the marriage registration authority may determine that the two parties have not reached an agreement on the custody of their children, and may refuse to accept it. According to Article 11 of the Marriage Registration Regulations, mainland residents who have applied for divorce registration shall present the following certificates and supporting materials:
 （1） My household register and ID card;
 （2） My marriage certificate;
 （3） A divorce agreement signed by both parties. The divorce agreement shall state the intention of both parties to divorce voluntarily and the consensus on matters such as child rearing, property and debt disposal. At the same time, according to the provisions of Article 12 of the Marriage Registration Regulations, the marriage registration authority will not accept the divorce registration of a party who has one of the following circumstances:
 （1） Failure to reach a divorce agreement;
 （2） Belongs to a person without or with limited capacity for civil conduct;
 （3） His marriage registration was not handled in the mainland of China. Is it illegal to have custody of children after divorce? When dealing with divorce issues, it is stipulated that if both husband and wife refuse to raise their children during divorce proceedings, the court may first rule that one party should temporarily support them. During the hearing of the case, both parties shall negotiate on the custody of their children, and determine which party shall be responsible for the custody according to the relevant provisions of the Marriage Law, and the other party shall pay the maintenance fees. In the case that both parties cannot reach an agreement and do not want children, if there are children less than two years old in the divorced family, the law generally stipulates that children live with their mothers after divorce, considering that the children are smaller and need more care from their mothers; If the children of divorced families are over two years old, the court should consider the situation of both parties regardless of whether they fight for the custody of the children, and see which party the children live with is more conducive to their physical and mental health, and is conducive to protecting their legitimate rights and interests. The court will consider to whom the child is to be raised from the perspective of facilitating the child's growth by combining the specific circumstances of both parents, including the economic conditions (including housing conditions), character, education, occupation, child's living environment and other factors. If the designated party refuses to perform the maintenance obligation, the court can take sanctions to force it to perform the obligation; If the circumstances of refusing to support are serious, it will also constitute the crime of abandonment.