The invention discloses a novel telescopic bird repelling blocking box. The box comprises a front part, a middle part and a rear part, wherein each of the front part and the middle part consists of a top plate, a bottom plate and two side plates; the rear part consists of a top plate, a bottom plate, a rear plate and two side plates; the front part, the middle part and the rear part are the same in length; every two corresponding side plates are right triangles with the same size; the top plates and the bottom plates are trapezoid; the rear plate is rectangular, and is vertical to the bottom plates and the side plates; the two ends of the bottom plate of the rear part are respectively provided with a through hole; the rear plate of the rear part can be detached; the front end of the rear part is provided with two bumps which are the same in length and face corresponding to each other; the middle part is provided with two bumps which are the same in length and face corresponding to each other. Through the mode, the telescopic bird repelling blocking box is simple in structure, easy to manufacture and convenient to use, the effect that birds are prevented from nesting is obvious, detachment is not needed, and the maintenance and overhaul of insulators by workers are convenient.