The study aimed to evaluate the effects of Karon 3 and 4 dams on land use and cover changes, for this aim 4 images over 28 years (taken in 1985, 2003, 2009 and 2013) were obtained and geometric, atmospheric and topographic corrections were applied. Maximum likelihood and post-classification techniques were used to detect land use/cover changes and their accuracy then was assessed using topographic maps and field works. The overall classification accuracy and Kappa statistics for all the maps were more than 0.79 and 86.24% respectively. The classification map of year 2009 indicated that about due to Karron3 dam and 6734.88 hectares because of rangeland and forest were destroyed. Classificated map of 2013 indicated about 5127.39 hectares increased because of Karon 4 too. The overall findings of this study indicate that forest and range land degradation in the region, is due to the construction of Karun 3 and 4.