The opening of the vulvar lips of a three-year-old girl is usually related to physiological factors, inflammatory infections and vulvar injuries. 1. Physiological factors: for example, insufficient secretion of estrogen in girls may lead to the opening of the vulvar lips. 2. Inflammatory infections: for example, bacterial infections, fungal infections and other microbial infections, when the pathogenic bacteria repeatedly stimulate the vulvar tissues, it is easy to lead to the splitting of the labia, and will be accompanied by vulvar redness, swelling and pain and other symptoms. 3. Vulvar injuries: such as bruises, bumps and so on, may lead to strong tearing of the vulvar lips, which will easily lead to the opening of the vulvar lips. More serious injuries can lead to poor healing after the labia are split open for a long time. Three-year-old girl vulvar labia opening, if it is caused by pathological factors, treatment should be carried out in a timely manner, so as not to delay the condition.