Hair follicles have a close relationship with sebaceous glands. The ducts of sebaceous glands open into the hair follicles and form a sebaceous gland system together with the hair, which can moisturize the skin and hair. 1. Sebaceous glands are important glands attached to the skin, located between the hair follicle and the erector spinae muscle, consisting of a secretory portion and a ductal portion, whose duct opens into the hair follicle. The sebaceous glands secrete sebum, which enters the hair follicle through the duct and then discharges it through the pore to the surface of the skin, where it can moisturize the skin and hair. 2. There are many factors that affect the secretory function of the sebaceous glands of the hair follicles, including neuroendocrine secretion, external temperature, humidity of the skin surface, age, gender, diet, and so on. If the skin leaves the sebum’s nourishment and nutrition, the skin will become rough and the hair will be dry and frizzy. It is recommended that patients who experience skin discomfort should seek medical attention in a timely manner to clarify the cause and follow the doctor’s instructions for treatment.