Abstract: Based on SODA, OAFlux and GPCP data, temporal and spatial distribution of sea surface salinity, freshwater flux and their relationships of the tropical western Pacific during 1980 to 2015 was analyzed with linear fitting,empirical orthogonal function decomposition (EOF),correlation and spectrum analysis.The results show that there is a good spatial correspondence between the climatic and transonic linear changes of SSS and freshwater flux. There are a variety of time-scale EOF modes,and their interdecadal modes are lag associated with the Pacific interdecadal oscillation (PDO). The result shows that PDO may affect the temporal and spatial pattern of SSS to impact the variation of Walker vertical circulation and the freshwater flux distribution in the tropical western Pacific.