This study dealt with monitoring changes in vegetation area in Wilayat Nizwa, Sultanate of Oman, using vegetation spectral indices, during the period from 2001 to 2018. Wilayat Nizwa was selected for its location in a distinctive ecosystem, which made it vulnerable to changes and influenced by natural and human factors. The study objective was to investigate and assess the causes of those changes in Wilayat Nizwa. The significance of the study is to provide spatial data and thematic maps for the vegetation cover in Wilayat Nizwa, which will help planning institutions in the Sultanate of Oman in general and the state of Nizwa in particular, in identifying and monitoring the affected areas and identifying appropriate methods for managing the vegetation cover. The study also provided proposals for dealing with vegetation cover and maintaining it and setting plans for its development and ensuring its sustainability. The significance of the study also lies in using modern technologies in an integrated manner in managing the vegetation cover in particular and natural resources in general, saving time and effort, and conveying the realistic image to decision makers in order to take appropriate solutions to the problems that are exposed. This study is based on image processing methodology using Erdas Imagine software for processing of Landsat imageries. And the application of vegetation spectral indices to determine the areas of vegetation, its locations and the use of geographic information systems (GIS) in the analysis of related data in order to reach an appropriate method to detect and assess the changes that occur in the vegetation cover in the study area. In addition, the use of the cartographic methods in producing change maps. The study acquired numerous results that determined the location of vegetation distribution in Wilayat Nizwa, as well as an increase in the area of vegetation cover during the study period. These results were supported by studying the change in the area of agricultural lands and analyzing the amount of rain for climatic stations of Wilayat Nizwa, which it turned out to increase during the study period. The study recommendations called for an effective use of spectral vegetation indices in studying the vegetation cover and monitoring its changes and the need to maintain and develop the vegetation cove as well as enforcement of laws and legislations that preserve natural resources.