The causes of hair graying are both physiological and pathological. Physiological factors include aging, excessive mental stress, etc. Pathological factors include albinism and progeria. 1. Physiological factors: (1) Aging: with age, the function of melanocytes in hair gradually declines and produces less and less melanin, resulting in hair that can no longer maintain white color. (2) Excessive mental stress: the metabolism will speed up when people are mentally stressed, and in this process, it will consume a lot of enzymes needed for melanin synthesis, leading to a decrease in melanin synthesis and the appearance of white hair. 2. Pathologic factors: (1) albinism: patients due to single gene genetic defects can not normal synthesis of melanin, thus leading to hair loss of color white. (2) vitiligo: the cause of the disease is not yet clear, may be related to heredity, autoimmune diseases, resulting in the destruction of skin melanocytes, pigmentation spots, if located in the scalp when the hair can be white. It is recommended that the hair white patients timely to the regular hospital, clear cause and diagnosis, and standardized treatment under the guidance of the doctor.