Assesment and monitoring of forest and rangeland is important and necessary for the management of these area. Nowaday, satelite images are used as a relatively low cost and rapid method to stady vegetation at different scales and by the evaluation of the spectral characteristics of plant their changes will evaluated as well. aim of is to this stady investigate change vegetation cover over in past two decates. Rangeland region semirom town located in Isfahan province, and also a forest area in lordegan town located in Chaharmahal and Bakhtiary province, Landsat images for this purpose in 1990, 1999, 2000, 2001, 2002 and 2009 year and also an AWiFS image (IRS-P6) for 2006 year were selected and processed. First, pre-processed including geometric and atmospheric corrections were applied on the images and then according to extracted vegetation cover data sampling time of vegetation cover 2009 image was selected to evaluate. In the stady area six vegetation indices using red and near infrared bands including NDVI, RVI, DVI, SQRT RVI, TNDVI and SAVI were calculated. the percentage of vegetation cover in regions was measured using step-point method with appranimatey (6000 point in each region) were statistical relationship between ground cover. Result data vegetation indice was done using analysis regression relationship were every high in each vegetation type and different vegetation type depending on their characteristics were more sensitive to vegetation indices. for example, Astragalus -Stipa barbata and Quercus branti type with DVI, and Bromus tomentellus type with, RVI and Astragalus - Daphne mucronata and Astragalus - Scariola orientalis type with NDVI, highly with the prcentage of vegetation cover showed (P 0/01). The resulte of this showed that relationship between the percentage of vegetation cover all vegetation type and vegetation indices were poor. These poor relationship might be as a result of spactral different in plant species and soil type. In the next stage of the stady, rainfall data and satellite images from last two decades were used for monitoring vegetation cover in different vegetation type. To investigate correlation between vegetation cover change in each vegetation type, NDVI index and the index which show the highest correlation with the present of vegetation cover was used. Also drouth effect were considered using standard percipitation index (SPI) and the amonth of rainfall. The results showed that all the rangeland vegetation had high correlation with spring rainfall data, although the amount of relationship were different in different vegetation type. The highest the highest correlation between spring precipitation with grasses (Br.to) was observed, but vegetation cover change in forest region was best . Key word : Vegetation cover, Vegetation indices, rainfall, SPI