The invention discloses a distribution-type optical fiber sensing system and a technical scheme, which are used to realize integrated on-line remote measurement of dam body-batholith internal deformation three components of a gravity dam, a dam body joint, and diastrophism, cracking, and extrusion of a bedrock tectonic belt, and is used to realize dam multidimensional-large scale spacetime full coverage. A plate-shaped beam of a novel optical fiber packaging structure---narrow rectangular section is provided, and the tension-compression sides of the plate-shaped beam are provided with microtubes to form an Euler elastic beam, and then the force-light direct conversion of the optical fiber is realized. An arrangement type of a sensing system in the gallery and the vertical shaft of the dam-bedrock, the comprehensive use of the sensing system, and an optical fiber laying technology are provided. The multifunctional integration of the optical fiber monitoring is achieved, construction is facilitated, the survival rate of the optical fiber is guaranteed, and application is convenient. An optical signal demodulation device adopts a high precision PPP-BOTDA or a hybrid Brillioun-Rayleigh system, and is multifunctional for being used for projects of monitoring a concrete temperature-reservoir water temperature, a slit position in front of a dam(factory), and a reservoir slit, and other optical fiber monitoring projects, and therefore upgrading and updating of a safety monitoring system are prompted.