An anal dilator (10) and an anorectal surgical instrument including the anal dilator (10). The anal dilator (10) includes a cylindrical body (10-1, 100) and an external light source assembly (20, 300) for illuminating surgical fields. The top of the body (10-1, 100) is an elastic enlarged edge (10-2, 200) and the external light source assembly (20, 300) is connected with the enlarged edge (10-2, 200). The anal dilator (10) is made of transparent materials. The surgical fields can be completely illuminated via a light path (101) by the light source during the surgery.
