The following conditions are considered: 1. It may be a pinworm infection, especially at night when the anal sphincter relaxes and the pinworm crawls out of the anus to lay eggs, so the sensation is stronger at night. 2. It may be perianal skin itching, which is caused by spicy and stimulating food that stimulates the patient’s anal canal and the skin around the anus. 3. The itching around the anus can occur due to contact with allergens. 4. It may be caused by viral and fungal infections of the skin around the anus, such as the common anal warts and anal eczema. 5. It may also be caused by perianal diseases such as hemorrhoids, anal fissures and anal fistulas. Considering that the cause is complex, if you feel more strongly, it is best to go to the hospital for medical treatment in time.