There are many causes of rectal vascular malformation, such as congenital developmental abnormality, chronic inflammatory stimulation, degenerative lesions and so on. 1. Congenital developmental abnormality: rectal vascular malformation is mainly caused by congenital developmental factors. 2. Chronic inflammatory stimulation: chronic inflammatory stimulation of the rectal canal can cause blood vessel stasis and dilation, thinning of the mucosa, and even the formation of necrosis, erosion, ulceration, which leads to rectal vascular malformation. 3. Degenerative lesions: age factors cause submucosal veins, degenerative changes may also lead to rectal vascular malformation. Rectal vascular malformation may have other causes, need to go to the hospital in time for further examination, clear diagnosis, if necessary, give reasonable treatment.