Children’s hair piece by piece thinning is mainly caused by diseases, common diseases include seborrheic dermatitis, rickets, occipital baldness and so on. 1. Seborrheic dermatitis: a common chronic inflammatory skin disease, the scalp’s sebum secretion will oppress and block the follicle holes. Patients often show a lot of dandruff on the head, erythema and hair loss and other symptoms. 2. Rickets: a chronic disease of abnormal calcium and phosphorus metabolism and osteoarthritis, vitamin D deficiency is a common cause. When the child lacks vitamin D can appear excessive sweating, irritability, poor sleep quality, tossing and turning at night and other symptoms, prolonged sweating and shaking the head can lead to constant friction of the hair and thus lead to hair loss. 3. Pillow baldness: Pillow baldness is a common type of hair loss in infancy and childhood, and the cause is often related to the hardness of the pillow, excessive sweating, eczema and other factors. The harder the pillow is, the more likely it is that baldness will occur, and the itching will cause the child to keep scratching and scratching, leading to hair loss. There may be other reasons for children’s thinning hair, so parents are advised to bring their children to regular hospitals to find out the cause of their thinning hair and follow the doctor’s instructions for treatment.