Irrigated land is one of the most important parts in land cover classification system

but until now it has seldom been reported about extracting it from remote sensing data and monitoring its dynamic change.The existing researches are focused on the land use-cover change（LUCC） and the irrigated area mapping

so the study on extracting irrigated land is much more im-portant.On the basis of close relationship between water deficit index（WDI） and soil water content

this paper firstly combines two neighbor NDVI and the surface-air temperature（Ts-Ta） and conforms one Vegetation Index Temperature（VIT）.It makes the timely incomparable WDI comparable and then computes the change of WDI during the monitored period.Secondly it infers the change of soil water.Thirdly it removes the rainfall’s influence under some assumption and extracts the irrigated land of the survey area.Results show that comparing with census data all the deviation is below 7% in the survey area except Shanxi prov-ince

which means that the extracted results are comparable with census data.Extracted irrigated land mainly distributes around rivers

lakes

and reservoirs or on the irrigated regions and oasises.The results are consistent with the centralized region which has abundant irrigated land known before.The results are checked elementarily using TM images.All the precisions are above 70% except in Shanxi province.The precision in Xinjiang municipality is the highest.