Bloodletting mainly refers to the use of trigeminal needles to pierce the body parts and release a small amount of blood to achieve the treatment of diseases. Its main function is to unblock the meridians, open the orifice and release heat, as well as reduce swelling and pain. In addition, the side effects of disinfection and prevention of infection must be done well. In addition, the blood should not be discharged continuously or in excessive amounts, usually 3-5ml is enough.