Many phenomena in the atmosphere and the ocean can be detected by sea surface winds.High quality and high temporal and spatial resolution sea surface wind data product is needed to study these phenomena.In this paper,sea surface winds from Cyclone Global Navigation Satellite System (CYGNSS) mission over 35°N-35°S are validated against in situ observations in order to evaluate the performance of CYGNSS.The in situ wind observations include measurements from the Xisha flux tower in South China Sea (SCS),and moored buoy data from the Global Tropical Moored Buoy Array (GTMBA).The result indicates a mean root-mean-square-difference (RMSD) of 2.17 m/s of CYGNSS winds with respect to in situ observations.Part of this discrepancy may come from instrument error,and part of it may come from representative error because of not-exact match of in situ and satellite measurements.The time evolution of CYGNSS winds,however,is consistent with that of in-situ winds,suggesting its potential application in understanding the complex mass and energy interchange processes of atmosphere and ocean.Examples using surface wind to analyze the MJO and the equatorial eastern Indian Ocean upwelling events are also discussed,which indicates potential applications of CYGNSS observation.