Abstract: Based on simultaneous MODIS data and the soil relative humidity data from April to August in 2005 in Xinjiang, models of soil relative humidity was established. The models were also based on the NDVI of season change and the correlation analysis of soil moisture in different arrangement as well as the difference in temperature by day and night. All the models passed the F test of the significance level of 0.01. The results showed that the precision of soil moisture was above 81% by using the thermal inertia method before June, but the precision was not satisfactory between June and August.

Key words: MODIS, NDVI, Soil relative humidity, Thermal inertia method