The invention discloses a device for reserving allowance for an anti-seismic optical cable at a deformation joint of tunnel arches. The device comprises a square shell and a circular shell, wherein the square shell is arranged on the deformation joint between the tunnel arches, and the circular shell is arranged in the square shell; a channel is arranged at an upper part of the circular shell, a support and a light spring are connected below the channel, and barbed steel sheets are uniformly distributed on the support; a fixed steel sheet is arranged at the lower part of the circular shell, and a round hole for the penetration of the support is formed in the fixed steel sheet, and a hard spring is connected below the fixed steel sheet. The device disclosed by the invention can be effectively adapted to the enlargement of the distance of the deformation joint of the tunnel arches, and solves an important technical problem for the safety monitoring of the tunnel traffic safety.