Sparrow spots are also known as freckles, whose main causes are related to genetic factors, sunlight exposure and gender and ethnicity. 1. Hereditary factors: Heredity is the main cause of freckles, which is usually autosomal dominant, and there will be family aggregation phenomenon. For example, if one of the parents has freckles, it may be passed on to the children. 2. Sunlight irradiation: prolonged sunlight irradiation may affect the outward appearance of freckles. Sunlight exposure or excessive exposure to ultraviolet rays may increase the incidence of this disease, and it will make the melanocytes in the skin larger in shape, and enhance the ability to produce melanin, which will deepen the color of freckles and increase their number. 3. Gender and ethnicity: the risk of female is higher than that of male, and the disease is more common in light-colored skin, such as white people. When the patients appear on the face after the sparrow spots, can cooperate with specialists to choose the way of laser treatment, do not blindly use drugs.