Abstract: Based on the data obtained from all the marine stations of State Oceanic Administration of China, and the ADCP and CTD data measured during "Tropical Ocean and Global Atmosphere (TOGA)", the northward flux of the sea water mass from the original sea-area of Kuroshio into the northwest Pacific Ocean (NWPO), and the water temperature and the sea surface level in NWPO and its adjacent seas are estimated and analyzed.In addition, the spacial and temporal variability of the latent heat flux through the sea surface of NWPO are estimated by use of the Goddard Earth Observing System(GEOS).It is shown from the results of the estimation that there is obvious interannual variability of the northward flux of the sea water mass.The relationship between this variability and the closely associated variabilities of water temperature, sea surface level, and the latent heat flux is the relationship between cause and effect.When the former one becomes decreased, the latter three will get obviously decreased.The physical explanation for the relationship between them is that the sea water mass and heat content transported from the western tropical Pacific Ocean into NWPO will make the water decrement and the total heat budget of NWPO decrease.Furthermore the heat budget decrease will in turn make the water temperature and the latent heat flux decrease.