The Mongolian Plateau (MP) plays an important role in the global carbon cycle and has significant impacts on the ecological security of northeastern Asia. Affected by land degradation and desertification, the vegetation cover on the MP experiences major changes under the influence of human activity and climate change. In contrast to previous holistic studies on the MP, this research focusses on the features of vegetation cover and divides the MP into three subregions (desert, grassland, and forest) to analyze vegetation dynamics and identify the driving factors behind vegetation change in this region. The residual analysis method is used and its “errors” are discussed. The results show the following. 1) The area of vegetation restoration is larger than the area experiencing vegetation degradation, and, overall, vegetation is greening and vegetation degradation is tending to reverse on the MP. 2) The ranking of vegetation change intensity is forest > grassland > desert subregions. 3) Climate change is the principal control on vegetation restoration across the whole MP, including the grassland and forest regions. Human activity similarly affects both vegetation restoration and degradation, but the effect of human activity is greater than that of climate change in the desert region. This research confirms that vegetation restoration activity is effective in the desert subregion of the MP.