Sea Surface Salinity (SSS) variability from a hindcast run of an oceanic general circulation model (OGCM) forced by daily NCEP-NCAR reanalysis from 1990 to 2001 is analyzed. The purpose is to test the capability of the model in terms of the salinity simulation and provide insights for the future SSS observation from space. With daily forcing, the model can reproduce SSS change of the tropical Pacific on different time scales by comparing with the Tropical Atmosphere Ocean (TAO) mooring observation. Our model results show that the western tropical Pacific is a large variability center on different time scales. On the interannual time scale, the standard deviation of SSS in the region could reach 0.5 practical salinity unit (psu). However, the eastern tropical Pacific shows relatively weak SSS variability (0.1 psu). On the intraannual time scale (60--360 days), the SSS variability in the western tropical Pacific is around 0.2 psu. The model SSS variability for the intraseasonal time scale (30--60 days) has a magnitude around 0.1 psu and tends to elongate along the latitudes of large meridional SSS gradient. On time scale shorter than 30 days, the model SSS variability center is near the equator and has a magnitude less than 0.1 psu. Relevance to the upcoming salinity satellite mission is discussed.