Abstract: Abstract: Drought is a recurrent complex phenomenon that affects nearly all climatic zones in the world. It is one of the major natural hazards in China, resulting in considerable economic, social, and environmental costs. Preparation for drought should be an important part of policies. Therefore, it is necessary to develop a dynamic and real-time drought monitoring approach in China. Remote sensing technology is one feasible way. However, the main drought indices of remote sensing for monitoring drought dynamics at present are based on visible and near infrared bands. They are always seriously impacted by rainfalls, clouds, vegetation, and terrain conditions. Hence, current drought monitoring technologies cannot meet the needs in south China, where the weather is always cloudy. Passive microwave emissions can penetrate non-precipitating clouds, thereby providing a better representation of land surface parameters under nearly all sky conditions. What is more, daily passive microwave data are available from microwave radiometers as compared to optical sensors like Landsat TM, ASTER, or MODIS, of which only weekly series products are available. So passive microwave remote sensing has unique advantages in long-time drought monitoring over those based on visible and near infrared bands. In this study, we first developed a semi-empirical model for retrieving land surface temperature using the AMSR-E C-band (6.9GHz) and X-band (10.7GHz) passive microwave remote sensing data. The approach provided a good retrieval accuracy of land surface temperature (error=2.54℃,R2=0.79). Next, this paper built an empirical relation between the AMSR-E 6.9GHz Microwave Polarization Difference Index (MPDI) and the NOAA-AVHRR Normalized Differential Vegetation Index (NDVI). Further, we improved the Vegetation Supply Water Index (VSWI) on the basis of the relation between NDVI and MPDI. Then, we used the new-developed drought index to monitor the drought dynamics of China in 2009. Results showed that many regions and cities of China (with red and yellow color) were attacked by the drought disaster in different degrees at the national level. The drought conditions were mainly distributed in Southwest (Yunnan, Guizhou and Guangxi Province, etc.), the Inner Mongolia Autonomous Region, northeast of Heilongjiang Province, Bohai region ( Liaoning, and Hebei Province), Jianghuai and Huanghuai region (Henan, Anhui, Shanxi and Shaanxi Province), and the Western region (Xinjiang Autonomous Region, Tibet Autonomous Region and Qinghai Province). The remote-sensed droughts were on the whole consistent with the actual situation of China in 2009 (http:www.gov.cn/jrzgv/). The field statistical data of the Meteorological Bureau showed that the average rainfall of China in 2009 was 565.8 mm, about 10 percent less than the same periods of past years (606 mm). What is more, the average temperature of China was 10.7℃ in 2009, about one degree higher than the same periods of past years (9.7℃). Analysis results indicated that sustained high temperatures and fewer rainfalls were direct factors that induced the serious drought disaster of China in 2009. The new drought index had a significant negative correlation with the corresponding AMSR-EL3 soil moisture data (R2=0.75; RMSE=0.02 g/cm3). In all, the drought monitoring method proved to be effective in describing the land surface drought conditions of China.