Scraping is based on the twelve meridians's theory and the principle of "treating symptoms and relieving emergency", which strongly stimulates meridians and makes local skin red and congested, so as to achieve the effects of waking up, detoxicating and eliminating pathogenic factors, clearing away heat and relieving exterior syndrome, promoting qi circulation and relieving pain, strengthening spleen and regulating stomach. The effects of scraping on skin can be divided into two categories, one is preventive health care and the other is treatment. The preventive and health care functions of scraping therapy include health care prevention and disease prevention. The function of scraping therapy is the skin on the body surface. Skin is the most superficial part of the human body exposed to the outside world, which is in direct contact with the outside world and plays an adaptive and defensive role in the change of the external climate. The skin has these functions, mainly relying on the function of defending qi in the body. Regular scraping by healthy people (for example, taking Beishu point and Zusanli point) can enhance the defense of qi. Strong defensive qi protects the exterior, and external evils are not easy to invade the exterior, so that the body can be healthy. If exogenous pathogens invade the exterior and interior, it will cause exterior and interior symptoms such as aversion to cold, fever, stuffy nose, runny nose, etc. Scraping in time (such as taking Shu Fei and Zhongfu) can eliminate exterior and interior pathogens in time and prevent them from being introduced into the five internal organs, which will lead to aggravation of the disease.