Hair loss in two and a half year old girls can be caused by normal metabolism, improper hair care, micronutrient deficiencies, and abnormalities in the scalp’s hair-growing tissues. 1. Normal metabolism: two and a half years old girl hair loss is relatively small, may be a normal metabolism, belong to the physiological phenomenon. 2. Improper hair care: two and a half year old girls do not wash their hair for a long time, wash their hair too often, use alkaline shampoo, poor quality shampoo, etc. Improper hair care may also lose hair. 3. lack of trace elements: two and a half year old girls usually excessive picky eaters, the body of malnutrition will cause the lack of trace elements, hair nutrition supply is insufficient, causing the local hair layer of hair loss, there will be the performance of hair loss. 4. Scalp hair tissue abnormalities: two and a half years old girl scalp fungal infection, resulting in scalp hair tissue abnormalities, local skin surface redness and swelling, there will be the phenomenon of hair loss. Two and a half years old girl hair loss causes more, hair fall more, to the hospital in a timely manner, active diagnosis and treatment, in order to avoid adverse consequences.