The empirical orthogonal functions analysis is applied to the time series of monthly hydrographic sections across Kuroshio near northeast of Taiwan. The EOF's of the first three modes account for 50-70% of the total variabilities. Physical processes revealed are cycles of the seasonal thermocline and halocline due to solar heating and shift of Kuroshio axis, the baroclinicity due to change of Kuroshio geostrophic velocity, the frontogenesis between East China Sea water and Pacific Ocean water due to orthogonal components of monsoon, and the upwelling induced by current geostrophy instead of the continental slope effect.