The invention relates to the technical field of accurate measurement of displacement, particularly to the technical field of settlement observation, and discloses a method and device for accurate measurement of large-range displacement and application. Through cooperative use of an area array CCD and a position guider, and through combination of two-stage displacement measurement, a distance measurement range is greatly expanded. The device provided by the invention is high in automation degree, the measurement accuracy reaches up to a micron grade, and the device has the characteristics of accuracy, rapidness and wide displacement measurement range. The device can be widely applied to a measurement process of large-range displacement offset, such as high-speed railroad subgrade settlement monitoring and tunnel deformation measurement.