The analysis of hydrology and morphologic characteristics of the Caspian Sea is main target in this paper. So by long term marine data analysis, the hydromorphology properties of Caspian Sea (morphology, fluctuation, temperature, salinity and transparency) have been studied. The main results show that the Caspian Sea as largest inland sea has unique morphologic condition and rapid sea level changing is the one of the most important natural process. The intensity of physical vulnerability and erosion risk in Caspian Sea is related to fluctuation rhythm and the spatial and temporal of marginal beach morphologic changing.