Yin and Yang are the basic core of TCM theory. Under normal circumstances, the human body maintains a relatively balanced state of Yin and Yang. If the balance of Yin and Yang is disturbed due to seven emotions and six evils, it will lead to pathological changes such as "Yin wins Yang disease, Yang wins Yin disease" and produce clinical syndromes such as "Yang is full of heat and Yin is full of cold". The key of scraping health care is to adjust the deficiency and excess of Yin and Yang according to the attributes of syndromes, so that the body can return to the secret of Yin and Pingyang and restore normal physiological functions, thus achieving the purpose of treating diseases.

The role of scraping in regulating yin and yang is basically achieved through the compatibility of acupoints and scraping techniques. For example, the disease is in the meridians, and the skin belongs to the surface, so it is necessary to scrape it lightly; The disease is in the viscera, the disease is in the bones and muscles, and it needs to be scraped again. Scraping can adjust the balance of yin and yang in both directions. For example, blood pressure is unstable, and hypotension can be increased after scraping acupuncture points on trunk and limbs. Hypertension can also be reduced.

(2) promoting blood circulation and removing blood stasis

Once the muscles, ligaments and bones of the human body are injured, there will be blood stasis locally, which will make the blood circulation in the meridians not smooth. Blood stasis does not go away, but the pain does not stop. At this time, scraping at local or corresponding acupoints can eliminate blood stasis, generate new blood, make the meridians unobstructed and blood circulation smooth, and achieve the purpose of general principle without pain. This is the function of scraping, promoting blood circulation and removing blood stasis.

(3) clearing away heat and reducing swelling

According to the principle of "heat is the cause" in traditional Chinese medicine, through the stimulation of heat-expelling method, the pathogenic heat can be induced out of the body to clear away heat, so that the pathogenic heat in Yang Can can penetrate the body surface and finally be discharged from the body, thus removing the blood stasis, heat and swelling in the body.

(4) Resolving phlegm and stopping spasm, softening and resolving hard mass.

For the body surface lump and wind syndrome caused by phlegm-dampness, the method of scraping and resolving phlegm can make phlegm-heat purulent leakage, and the effect of stopping spasm and resolving stagnation is obvious.

(5) strengthening body resistance and eliminating pathogenic factors

Scraping will change the skin of the corresponding acupoints, resulting in bruising and purplish red blood stasis, which will open and dredge the acupoints, expose wind, cold, phlegm, dampness, blood stasis, fire and poison stuck in the meridians and corresponding tissues and organs from the fur, and dredge the meridians.