The main causes of soft hair are congenital factors, improper hair care and other non-disease causes, but also endocrine abnormalities, trace elements or vitamin deficiencies and other pathological causes. A, non-disease factors 1, congenital factors: the softness of the hair is generally related to genetic factors, parents with soft hair children’s hair is also soft. Some women due to pregnancy reaction during pregnancy is more serious, resulting in insufficient nutrient intake, the baby will be born with soft hair performance, gradually will improve; 2, improper hair care: washing hair when the water temperature is too high, frequent perming, the use of intolerant shampoo, hair dye, hair follicle injury resulting in insufficient absorption of hair nutrients, hair will become soft, dry, split ends, fall off. Second, pathological factors 1, endocrine abnormalities: for example, androgen excess of the population, the early top of the head of hair can become thin and soft, curved, most of the hair follicles stop growing, later can appear hair follicle volume reduction, density reduction, hair thinning. In addition, low thyroid function, low parathyroid function, insufficient secretion of growth hormone can also cause metabolic disorders, resulting in insufficient supply of nutrients to the scalp and the phenomenon of fine hair; 2, trace elements or vitamin deficiency: such as iron deficiency anemia, zinc deficiency can cause fine and soft hair.