Article 1170 of the Civil Code introduces the mother's remarriage as one of the obstacles to custody. Article 45 of the Family Protection Law, which states that the best interests of the child must be taken into account in all judicial and executive decisions, does not restrict the application of this article. Judicial practice is also organized based on this application. In this article, after analyzing and examining the best interests of the child, the jurisprudential foundations of this article, and examining the results of some research on the harms of separation of a child from his mother, we want to take a step towards proving that the best interests of the child require that the mother's remarriage alone should not be considered an obstacle to his custody. It is necessary to decide in each case, taking into account the family circumstances, the mental and psychological characteristics of each child, and the degree of the child's dependence on his parents, which parent is in the best interests of the child. Therefore, it is possible to use the capacity of government decrees issued based on the interests of Islam and Muslims to amend Article 1170 and make it subject to the need to observe the interests of the child. In this regard, the legislator can amend and supplement Article 45 of the Family Protection Law to reform its judicial practice in the enforcement capacity.