The utility model discloses a measurement system of vertical displacement of rail. Wherein, this system includes: communication relationship is establish with laser emitter to the controller for the lasing of control laser emitter, the scale is fixed in the rail for receive the laser of laser emitter transmission, image sensor establishs communication relationship with the controller for the firstimage of the scale that will gather sends to the controller, wherein, and including the light beam of laser in the first image, the controller still is used for generating vertical displacement of rail according to first image. The utility model provides an in the correlation technique, detect the poor technical problem that data accuracy nature is low that detects of leading to of the device vibration resistance of rail displacement.