A grating manufactured by a micro-structure gap control technique is provided in this invention. The grating includes a first structural part, a second structural part and a substrate. The first structural part includes a first micro-structure and a concavity, the second structural part includes a second micro-structure and an island structure located within the concavity, wherein a gap exists between the inland structure and the concavity. Further, the substrate is bonded to the first structural part and the second structural part for supporting the first structural part and the second structural part.