The invention discloses a flexible grille support and an application method thereof. The flexible grille support comprises a single arch frame which is formed by welded main reinforcing steel bars and stirrups and consists of multiple sections, and the main reinforcing steel bars of adjacent sections are connected by at least one support clamping cable; the support clamping cable is structurally characterized in that reinforcing steel buckles with same quantity as the main reinforcing steel bars of the grille support are welded by virtue of connecting ribs, each reinforcing steel buckle is formed by two splint plates which are in butt joint by virtue of connecting pins and bolts, two circular holes are formed in the abutting surfaces of the splint plates, the main reinforcing steel bars of two sections are inserted into the circular holes from two sides, and a certain pretightening force is applied through the bolts. Compared with other metal flexible supports, the flexible grille support has the advantages of small steel consumption, low cost, light weight, and convenience for transportation and installation; and meanwhile, a flexible critical internal force can be manually controlled.