Based on the land surface temperature data figured out of the composite data of channel 4 and channel 5 light temperature of NOAA-AVHRR, together with spectrum vegetation indices, water deficit index (WDI) was estimated as the indicator of drought.The spatio-temporal characteristics of droughts and drought occurrence frequency of each month in China in the past two decades (1982~2001) were analyzed.Results showed that in spring, Northwest China, North China and South China had a higher drought occurrence frequency; from May to August, Northwest China and North China had; and from September to December, Northwest China, North China, Central China and Sichuan basin had.The analysis of relationship between average annul precipitation and average WDI, drought occurrence frequency in the 20 years demonstrated that they were closely related in a linear pattern when the average annul precipitat ion was less than 500 mm but when the average yearly precipitation was more than 500 micro-metal, WDI was not distinctly related to precipitation and drought level.