Abstract: The perpendicular drought index(PDI) and modified perpendicular drought index(MPDI) were applied and compared over the vegetation area of Ming'an town,Inner Mongolia,based on TM imagery.The results show that the determination coefficient of PDI,MPDI with the measured soil moisture are 0.37,0.535 5 respectively.PDI and MPDI are both feasible for drought monitoring in our study area,and the monitoring precision of MPDI is higher than PDI.In addition,the comparison of the drought mapping of the two indexes,and the analysis of the variation trend of the two indexes with the soil moisture both indicated that monitoring results of the two indexes are similar in the whole test area,but in vegetation area,the precision of drought monitoring of MPDI is superior to PDI,this is mainly due to the vegetation impact considered in MPDI.