Abstract: The prototype observation items of the power plant at Xikou pumped storage power station include strain of concrete, strain of sheet-metal casing, stress of steel bar, and seepage of sidewall and foundation. Based on the observation data from the date of embedment of instruments settlement to the end of 1999,the characteristic values and the regularities of the observed variations are analysed. The comprehensive evaluation shows that the operation situation of the power plant is normal.?