The invention relates to the technical field of engineering detection, and specifically relates to a crack dislocation displacement measurement system and a measurement method; the system comprises afirst fixing assembly fixedly arranged on a first monitoring surface, a stay wire type crack meter arranged on the first fixing assembly, a pulley rotationally arranged on the first fixing assembly and a second fixing assembly fixedly arranged on a second monitoring surface; the stay wire type crack meter comprises a body, a flexible stay wire, a sensor and an information module, wherein one end of the flexible stay wire is connected with the body in a sliding manner; the sensor is arranged in the body and used for monitoring the moving distance of the flexible stay wire; the flexible stay wire is wound on the pulley; the end, away from the body, of the flexible stay wire is connected with the second fixing assembly, and the flexible stay wire located between the pulley and the second fixing assembly is perpendicular to the second monitoring surface. The crack dislocation displacement measurement system can monitor the dislocation displacement of the monitored object in the direction parallel to the crack surface.