Abstract: In order to meet the requirements in practical work, this paper proposes a laser traverse system, which can be used to measure the displacements of arch dams or curved structures. The paper discusses in much detail the principles of the system, the design concept of bend-angle prisms, the effect of the errom in installation of the prisms on the accuracy of determining variation of angles of bend, the observation method of the system, and the computation of the displacements of arch dams.