The processing method of applying for declaring the marriage invalid:
 1. The people's court will not accept a lawsuit filed by a party only on the ground that one party violates the duty of fidelity between husband and wife (Article 4 of the Marriage Law); If the case has been accepted, it shall rule to dismiss the prosecution.
 2. If the party concerned applies to the court to declare the marriage invalid according to Article 10 of the Marriage Law, and the legal invalid marriage situation has disappeared at the time of application, it shall not be supported.
 3. Within one year after the death of one or both of the husband and wife, the people's court shall accept the application of the surviving party or the interested party to declare the marriage invalid in accordance with Article 10 of the Marriage Law.
 4. If the interested party is the applicant for the lawsuit of invalid marriage, both parties to the marriage are the respondent; If one of the husband and wife died, the surviving party is the respondent; If both husband and wife are dead, the respondent shall not be listed.
 5. Relationship with divorce lawsuit: after the court accepts the divorce case, if it is found that the marriage is invalid in the review, it shall make a judgment declaring the marriage invalid; If the court has accepted divorce and invalid marriage declaration applications for the same marital relationship, it shall first make a judgment on the latter before proceeding with the divorce case; Once the marriage is declared invalid, the trial should continue on issues involving property division and child rearing.