It can be negotiated by both parties. If the negotiation fails, it can be sued. Generally speaking, the ownership of custody will be determined according to the following principles:
 1. Children under the age of two are generally awarded to the woman.
 2. Children over two years old will give priority to the one with better conditions to raise their children.
 3. If a dispute arises over a minor child over the age of 10 who follows his or her father and mother, the child's own opinion shall be taken into consideration.
 [Legal Basis]
 Article 1084 of the Civil Code states that the relationship between parents and children shall not be eliminated by parents' divorce. After divorce, whether the children are directly raised by the father or the mother, they are still children of both parents. After divorce, parents still have the right and obligation to support, educate and protect their children. After divorce, children under the age of two shall be directly supported by their mothers in principle. If both parents fail to reach an agreement on the upbringing of a child who has reached the age of two, the people's court shall make a judgment on the basis of the specific circumstances of both parties and the principle that it is most beneficial to the minor children. If a child has reached the age of eight, his or her true wishes shall be respected.