The adhesion judgement formula of the mirror with clamped beams is derived by the theoretical and numerical calculation. In design phase of the MEMS structure, it is difficult to judge the structure adheres to the substrate or not except circle plates or beams, and the adhesion design is liable to become trial and error. We point to a mirror with clamped beams as an example of an adhesion problem of the complicated structures, and have tried to derive the adhesion jugdement formula of the mirror with clamped beams we can jugde the mirror adheres to the substrate or not by using the dimension of the mirror and the adhesion energy between the mirror and the substrate.