The variation features of total amount of water resource and the runoff as well as underground water level were studied through analysing the historical tendency,stage and periodicity of water resources in Shandong Province. The results showed that the interannual change was great and water resources decreased rapidly,especially the amount of runoff. Certain stages and periodicities existed in the variation of water resources. The changing regularity of precipitation and water resources was consistent in terms of the relations between them,but the influence of rainfall on water resources,especially underground water,were successive to some extent. The forecast made by mean generation function demonstrates that the total amount of water resources from 1998 to 2000 will be still less than usual and decline gradully year by year.