Abstract: A procedure is proposed to analyze the random response of arch dam subjected to spatially correlated seismic excitations. The earthquake ground field is expanded into a set of independent random processes. The developed massless foundation model is also taken into consideration. The proposed approach can deal with random correlative problems, canyon seismic amplification and wave-propagation effect problems, and even the dam-foundation- reservoir non-classic damping problems. An numerical example is provided to demonstrate the proposed procedure. It is shown that the procedure is very effective in random seismic analysis of large structures suds as dams.