The causes of hair loss include genetic factors, autoimmune factors and mental factors. 1. Genetic factors: this situation is most common in androgenic alopecia. Clinically, the hair loss follicles of people with this condition are more sensitive to androgens, and are susceptible to follicle shrinkage after hormonal stimulation, which manifests itself as hair loss symptoms. 2. autoimmune factors: this situation is most representative of spot baldness, this group of people will also be combined with autoimmune diseases, such as thyroid, vitiligo and so on. 3. Mental factors: Some people suffer from shrinkage of scalp hair follicles due to excessive mental stress, which manifests itself as hair loss. Some children have hair pulling fetish, which will also cause damage to the scalp hair follicles and manifested as hair loss symptoms. It is recommended that people with this condition should go to the hospital to find out the cause, so as to carry out targeted treatment.