The invention relates to a method and device for field observation of soil layer frost heaving of a high speed railway in a seasonal frozen soil region. An optical instrument used for observing seasonal frozen soil layer frost heaving amount cannot be used for observing the frost heaving amount of all layered soil in the freezing depth, precision is hard to meet, and professional instruments and observation technicians are needed for observation. The device is buried in a seasonal frozen soil layer and comprises a round-sheet-shaped lower anchor disc and a round-sheet-shaped upper anchor disc. A vertical measuring bar displacement meter is connected to the center of the lower anchor disc and the center of the upper anchor disc, and the measuring bar displacement meter is connected with a reading instrument arranged outside filled soil above the upper anchor disc through a transmission cable. Frost heaving deformation of the seasonal frozen soil layer drives the upper anchor disc and the lower anchor disc to move, and the measuring bar displacement meter is used for observing the variable quantity of the distance between the upper anchor disc and the lower anchor disc to reflect the frost heaving amount of the seasonal frozen soil layer. By means of the method and device, the total frost heaving amount of the seasonal frozen soil layer can be observed, and the frost heaving amount of all layered soil can be observed by setting devices of different lengths; the displacement meter is high in observation precision and efficiency, and automation of observation of frost heaving deformation can be achieved.