By integrated analyses of the vegetation index and surface temperature, more useful information can be acquired. The method of the vegetation index-surface temperature feature space has being widely used in some fields. From the point of view of regional drought monitoring, the ecological connotation of the feature space was analyzed, which indicates that the surface temperature is a function of surface evapotranspiration. The method of temperature evapotranspiration dryness index(TEDI) was derived. Using NOAA data, through the method of temperature vegetation dryness index(TVDI) and temperature evapotranspiration dryness index(TEDI) respectively, the drought status of south plain in Hebei Province was studied. The results were validated by the soil relative humidity index(SHI) measured on the ground at the same time, which shows that the method of temperature evapotranspiration dryness index(TEDI) is more accurate than the method of temperature vegetation dryness index(TVDI) in the monitoring of the status of regional soil water content.