Abstract: China's new generation of polar-orbiting meteorological satellite FY-3A was successfully launched on May 26th, 2008, carrying microwave sounding units which had similar performance to ATOVS of NOAA series. In order to study the application of Microwave Sounding data in numerical prediction of typhoons, directly assimilate the microwave sounding data of FY-3A satellite, and improve typhoon forecasting, we conducted numerical predictions of track and intensity of typhoon Morakot (2009) and carried out research on direct data assimilation technology, based on FY-3A microwave sounding data and WRF-3DVar System. Results show that direct assimilation of FY-3A microwave sounding data improves the initial fields of a regional numerical model much more than assimilation of conventional observations alone, which is especially significant in the ocean where there is always lack of conventional observations. The model fields are more reasonable in reflecting the initial typhoon circulation as well as temperature and humidity conditions, and typhoon centre position at sea has also been adjusted. Through direct 3DVar data assimilation of FY-3A Microwave, the regional mesoscale model has positively improved the forecasting of typhoon track. FY-3A microwave data can efficiently improve the ability of numerical prediction of typhoons.