Abstract: Deformation is a key indicator for analyzing the characteristics and evaluating the safety of embankment. In this research, the installation method of sensing fiber equipped with an auxiliary structure was designed for the distributed monitoring of embankment’s internal two-dimensional deformation. A distributed monitoring test was conducted on a prototype embankment and the test result of its internal deformation validated the measurement accuracy and feasibility of the distributed monitoring technology as the maximum absolute error between the test result and the actual measured result of the embankment’s two-dimensional deformation was 4.3 mm; and mm-level measurement accuracy was realized not only for the internal two-dimensional deformation at certain points, but also for the whole section of the embankment, which proves the applicability and advancement of the fibre-optical distributed monitoring technology of the two-dimensional deformation inside the embankment.