The present invention discloses a dynamic diagnosis system and method for concrete damage based on a distributed sensing optical fiber. The system includes an upper fixed platform and lower fixed platforms, the upper fixed platform is provided with an optical fiber correction entity and an optical fiber framing platform, the optical fiber correction entity is provided with a butterfly-shaped optical fiber pressing block, the optical fiber framing platform is provided with an optical fiber threaded column, a sensing monitoring barrel and a disturbance eliminating barrel are arranged below the upper fixed platform, the downside of the sensing monitoring barrel is connected with a left fiber fixing beam, the left fiber fixing beam is connected with a left barrel bottom cone, the left barrel bottom cone is hinged with a left port light source protection body, the lower end of the disturbance eliminating barrel is connected with a right fiber fixing beam, the right fiber fixing beam is connected with a right barrel bottom cone, and the right barrel bottom cone is hinged with a right port light source protection body. The dynamic diagnosis system and method are not only capable of catching microvibration, but also capable of bearing greater-amplitude vibration, so that the vibration monitoring range is greatly widened, and the demand for dynamic diagnosis of concrete structural damage is met perfectly.