To further understand the ecologic restoration level after water supplying，the authors studied vegetation coverage （Fv）in the water supply area of the lower reaches of the Tarim River. Correlation equation and two-dimensional scatter plot between Fv and vegetation index （VI） could be obtained based on MODIS data by constructing a variety of VIs in combination with measured Fvs，and the value of Fv could be figured out based on the relevant equation. The results show that there exist good correlations between the VIs such as NDVI，MSAVI，SAVI and EVI and Fvs on the basis of MODIS data. With these VIs，the inversion accuracy of the Fvs in the order from higher to lower is NDVI, EVI, MSAVI and SAVI. The authors suggest using MODIS data to monitor vegetation change in the arid desert area，with the optimal choice of VI being NDVI.