Abstract: Four murder cases of paranoid psychosis are reported in the present paper. As this kind of mental disorder is relatively less common and the symptoms of it are not so remarkable as to be easily recognized, the characteristics, especially clelusion of jealousy have been discussed. And the law problems, such as evaluation of criminal responsibility, etc, have been put under discussion too. It is summarized that in the work in identification the symptom of dlelussian of jealousy has to be firstly noticed in this case, the patient has no criminal responsibility at all.