It may be caused by a simple unconscious throbbing of the muscles, or it may be caused by anal diseases or rabies. The unconscious throbbing of the muscles is usually episodic and is not accompanied by other uncomfortable symptoms, and the symptoms will disappear after a little time. Anal diseases such as hemorrhoids, perianal eczema and ringworm can cause itching in the anus, which can repeatedly stimulate the perianal skin and cause strong itching in the perianal skin, causing local nerve reactions and giving the patient the illusion that something is crawling in the anus, and there are usually other accompanying symptoms, such as hemorrhoids with anal swelling and blood in the stool, perianal eczema with thickening and deepening of the perianal skin, and ringworm with inflammation. In addition, in the case of pinworm infection, the patient may feel worms crawling around the anus and rectum due to the activity of the worms.