Abstract: The results of prototype observation of Lubuge Dam in the deformation, seepage and soil pressure from Jan. 1987 to June, 1991 are presented comprehensively in this paper. The dam is safe after first normal high water level. But some unsafe factors should be noticed, for example, the shear and tensile deformation near the two side bank are greater, the connection of the core and concrete course in the side bank is loose, the seepage condition of contact face is worse and the crack is produced at the top of dam.