Natural ecosystems are highly affected by anthropogenic activities and environmental factors. The aim of this study was to detect land use/cover and vegetation decline in Chaharmahal and Bakhtiari province, using Landsat different satellite imageries. For this purpose, images for 1993, 2009 and 2016 were obtained and the geometric, atmospheric and topographic corrections were applied. Land use/cover maps and vegetation decline regions were extracted, using maximum likelihood classifier with an overall accuracy and Kappa coefficient of 82% and 0.79 respectively. Results showed that the area of rangelands and forests has decreased from 358355 to 174735 ha and from 357190 to 343970 ha, respectively. Results also indicated that around 33937 ha of forests and rangelands have been declined in the last 23 years. According to the findings, an urgent and appropriate management of declining rangelands and forests is necessary across the study area. In this regard, developing a simple and applied vegetation cover monitoring software, based on satellite images, is recommended.