In general, there are vegetables that promote defecation, such as leeks, sweet potatoes, cucumbers, etc., but there is no fastest defecation vegetables. 1. leek: rich in crude fiber, not easy to be digested and absorbed by the gastrointestinal tract, helps to increase the volume of feces and prevention of dry stools, and can promote gastrointestinal peristalsis, help defecation. 2. Sweet potato: belongs to the coarse grain food, rich in dietary fiber. Dietary fiber is conducive to the absorption of water in the intestinal tract, assisting in increasing the volume of feces to stimulate the intestinal wall, causing increased intestinal peristalsis, which is conducive to the excretion of feces. 3. Cucumber: rich in dietary fiber and vitamins, is conducive to increasing gastrointestinal peristalsis, and is rich in water, not only can lubricate the intestinal tract, but also promote defecation, assisting in relieving the symptoms of defecation caused by dry stools. 4. Mullein: rich in vitamins, fiber, etc., helps to lubricate the intestinal tract and promote gastrointestinal motility, play a role in the prevention and relief of constipation. Can also be strengthened through exercise, local massage abdomen, drink more water and other ways to promote defecation, if the defecation situation can not be improved, it is recommended to consult a doctor in a timely manner in order to clarify the diagnosis, under the guidance of the doctor for targeted treatment.