Anti-fuse structure circuit and method of forming an anti-fuse structure circuit are provided. A substrate is provided, and an anti-fuse is formed on the substrate by forming a first gate structure and a dielectric layer on the substrate and forming conductive plugs respectively in the dielectric layer at two sides of the first gate structure. The dielectric layer covers the first gate structure, and the conductive plugs have a width decreasing from top to bottom. A second gate structure is formed on the substrate. A top surface of the first gate structure is higher than a top surface of the second gate structure. The dielectric layer also covers the second gate structure. The conductive plugs are also located respectively in the dielectric layer at two sides of the second gate structure.