Excessive medical treatment is a violation of the medical institutions obligations to provide reasonable diagnosis and treatment and a medical service that exceed the actual treatment required by patients. The controversy in practice focuses on the identification of medical damage liability arising from excessive medical treatment. Excessive medical treatment in violation of the obligation of reasonable diagnosis and treatment is the premise for medical institutions to assume the liability for damages，and the causal relationship between damages and excessive medical treatment is the basis for the establishment of liability for damages. Because excessive medical treatment has the attribute of tort，there are four elements for medical institutions to bear the liability for damages. First，in terms of subject suitability，the actor is a legitimate medical institution. Second，in terms of the nature of the act，there is excessive medical treatment judged by medical science. Third，in terms of the result of the act，it causes damage to the patient. Finally，in terms of the establishment of liability，there is a causal relationship between the damage and excessive medical treatment.