Spouses who are mentally ill can sue for divorce. The mentally ill person belongs to the person with limited capacity for conduct, and the spouse is the first guardian of the mentally ill person. Therefore, it is necessary to change the guardian before filing a divorce lawsuit, and then file a divorce lawsuit to the court. If the ordinary court considers that the relationship between the two parties is broken and the mediation is invalid, the divorce shall be granted.
 Legal basis:
 Article 28 of the Civil Code of the People's Republic of China
 An adult with no or limited capacity for civil conduct shall serve as guardian in the following order:
 （1） Spouse;
 （2） Parents and children;
 （3） Other close relatives;
 （4） Any other individual or organization willing to act as guardian shall, however, obtain the consent of the residents' committee, the villagers' committee or the civil affairs department in the place where the guardian resides.
 Article 1079 of the Civil Code of the People's Republic of China
 If one of the husband and wife requests divorce, the relevant organization may mediate or directly file a divorce lawsuit with the people's court.
 When hearing divorce cases, the people's courts shall conduct mediation; Divorce shall be granted if the relationship has really broken down and mediation has failed.
 Divorce shall be granted if mediation fails in any of the following circumstances:
 （1） Bigamy or cohabitation with others;
 （2） Domestic violence or maltreatment or desertion of family members;
 （3） Gambling, drug abuse and other bad habits persist in teaching;
 （4） Two years of separation due to emotional discord;
 （5） Other situations that lead to the breakdown of the relationship between husband and wife.
 Divorce shall be granted if one party is declared missing and the other party files a divorce lawsuit.
 Divorce shall be granted if one party files a divorce lawsuit again after the people's court has ruled that divorce is not allowed and the two parties have lived apart for one year.