"Knife Healing" is one of folk treatments in Taiwan. Using keen chopper to chop on the body to cure diseases. This article propose "why do people choose Knife Healing to cure their diseases and believe the efficiency of Knife Healing"? Firstly, why to choose "Knife Healing" studies based on opinions among folk treatments, western and Chinese medicine, and "Knife Healing" knowledge of patients and interaction of healers and patients and regional brief. Secondly, study how do "Knife Healing" be convinced today? There are medical, internet, regional brief, psychology and some problems hidden behind the behave and social culture. Therefor, we interviewed ten patients who accepted the treatment of "Knife Healing" and recorded not only the reasons that they chosen and process of "Knife Healing" treatment, but also their viewpoints. Meanwhile, we also interviewed three "Knife Healing" healers who used to be patients to know the goal of creating the "Knife Healing" association and structure and operation of it. Further, we interview six doctors including herb doctors to know their opinions about "Knife Healing" and help us to understand some medicine questions related to "Knife Healing." Finally, We find the patients cured by "Knife Healing" interrelate very much among folk treatments, medical, knowledge, interaction of healers and patients and regional brief. Especially offering a good explain in reducing the paint in pathology after "Knife Healing." Apparently, common brief on both healers and patients cause well psychology and social efficiency on the treatment of "Knife Healing." When chopper is chopped on the patient, magic treatment has been resulted already. All of this should be belong to religion brief. The research of "Knife Healing" fulfilled the possibility and important of the behavior of "Knife Healing." And also can provide academia and medicine for reference further.