There are more reasons for anal pain after defecation, and the nature of the pain is also different, the more common reasons are the following: 1, the stimulation of bad diet, over-eating spicy, alcohol, will stimulate the anus to cause pain, reduced intake of vegetables and fruits, easily lead to dry stool, triggering constipation, increased difficulty when defecating, resulting in anal pain, and even can cause anal tears. 2, perianal infection, such as perianal abscess, The pain can be caused by the inflammatory stimulation due to the squeezing effect when defecating. 3, diseases of the anus, such as internal and external hemorrhoids, anal fissures, anal fistula and other diseases, in addition to pain when defecating, there will be blood in the stool. 4, diarrhea, frequent diarrhea, stimulation of the anus causes pain. 5, anorectal tumor, tumor compression of the anus at the same time, can cause inflammation of the rectal anal mucosa, when defecating cause pain.