The disappearance of the anal canal reflex belongs to one of the superficial reflexes of the human nerve reflexes, the person lies flat, the lower limbs are raised and straightened, and the external anal sphincter will be contracted by a small needle crossed in the perineal area. The afferent nerve is the pubic nerve, and the center is in the posterior horn cell column of the sacral medulla 4-5 and the anterior horn cell sex of the same segment. The external anal sphincter receives bilateral innervation from the perineal nerves. When one side of the pyramidal tract is damaged or the peripheral nerves are damaged, the anal reflex still exists, and when both sides of the pyramidal tract are damaged or the cauda equina is damaged, the anal reflex disappears. Fecal incontinence in the elderly may show loss of anal reflex. It is characterized by varying degrees of loss of control of defecation and evacuation. Patients with mild incontinence have loss of control of evacuation and liquid feces, with occasional soiling of their underwear, and patients with severe incontinence also have no control of solid feces, which is manifested by frequent anal evacuation of feces, which can be avoided by avoiding soiling of the clothing and pants if the patient is able to find a toilet quickly. The quality of life and physical and mental health of patients with this disease are often affected by the prolonged wetness and uncleanness of the perineal area, which contaminates clothes, pants, bed sheets, and so on. Physical examination reveals moist and unclean anal perineal area, eczema ulcer scarring, perianal skin scarring anal laxity, and sometimes rectal prolapse. Finger examination can touch hard fecal mass or tumor, etc. There can be anal sphincter relaxation and stretching, and its contraction force is weakened or disappeared. Careful examination can accurately determine the location of the contractile weakness and may show loss of anal canal reflexes.