Desertification is one of the most severe environmental issues facing the world today, and effective desertification monitoring is critical for understanding its dynamics and developing prevention and control strategies. Although numerous studies on desertification monitoring using remote sensing have been conducted, there remain differences in indicator selection, and a unified monitoring system has yet to be established. In this study, we constructed the Desertification Composite Index (DCI) using Landsat satellite images, integrating six remote sensing indicators reflecting the natural and ecological characteristics of desertified areas. We also incorporated 383 UAV imagery datasets to accurately identify and analyze the spatial and temporal distributions of desertification in the Ring-Tarim Basin from 1990 to 2020 and subsequently assess its spatiotemporal trends. The results show the following: (1) The constructed DCI was used to identify desertification in 2020, achieving an overall accuracy of 0.86 and a Kappa coefficient of 0.8, indicating that the DCI is suitable for extracting regional desertification information. (2) From 1990 to 2020, the area of desertification decreased significantly, with an average annual reduction rate of -0.0022 ha/a, indicating continuous ecological improvement. Despite localized deterioration, the overall trend was one of general improvement and local containment. (3) GeoDetector-based analysis showed that cultivated land area and land use type were the primary single-factor drivers of desertification. The interaction between cultivated land and vegetation type exhibited a synergistic effect as a two-factor driver. (4) Desertification in the Ring-Tarim Basin is primarily influenced by human activities. Appropriate management and intervention measures, efficient and intensive cropland management, and rational land use planning can help develop effective strategies to combat desertification.