The pulse comes to be thin, soft and sunken, soft and slippery pulse. Weak pulse is mostly seen in deficiency evidence of Qi and blood deficiency. If the blood is deficient and the pulse is not full, the pulse is thin; if the qi is deficient, the pulse is weak, and the pulse is sunken and soft and weak. Weak pulse is due to the deficiency of yang qi and yin blood, qi and blood are unable to spread outside and the pulse is sunken; the pulse is thin and weak due to the weakness of filling and drumming. It is certain that the weak pulse is dominated by Yang deficiency, Qi deficiency and Blood deficiency. Is the weak pulse main yin deficiency? The yin deficiency mentioned here refers to yin deficiency in a narrow sense, which refers to yin deficiency accompanied by bone steam and tidal fever, night sweats, irritable heat in the five hearts, red cheekbones, and a reddish tongue with little moss. Generally speaking, in the case of Yin deficiency and internal heat, the pulse should be floating and fine, and a weak pulse should not be seen. Weak pulse can occur due to malnutrition, commonly due to iron deficiency and folic acid deficiency. In addition, anemia is one of the main causes of weak pulse, mainly due to deficiency of qi and blood, which is closely related to the spleen, stomach, liver and kidney. The spleen and stomach are the source of Qi and blood biochemistry: the spleen and stomach are the basis of the latter. Diet is transformed into Qi and blood through the transportation and transformation of the spleen and stomach to produce water and essence. Essence and blood are of the same origin: the kidney is the origin of the innate nature, the kidney is the main reservoir of essence, essence produces marrow, essence and blood regeneration.