When women suffer from these gynecological inflammatory diseases, the inflammation can lead to an increase in the permeability of the skin mucosa and blood vessels in the lesioned area, resulting in the leakage of substances in the blood, as well as the secretion of substances, which can lead to the black surface of the vulva and the red inside, Second, it may be due to the endocrine system problems, because the endocrine system of girls is very developed, can secrete a variety of hormones, such as estrogen, sex hormones, progesterone, follicle stimulating hormone, luteinizing hormone, etc., if the content of these hormones is too high can lead to the vulva surface black, red inside.