Quantitative assessment the impact of natural factors and anthropogenic factors on grassland ecosystem changes is vital to grassland scientific protection and restoration. Therefore, this paper reviewed and summarized the quantitative assessment methods which are widely used at present, including principal component analysis (PCA), analytic hierarchy process (AHP), residual trend (RESTREND) method and ecosystem model method (difference between remote sensing model and process-based ecosystem model or climate-productivity model). We focused on comparing the algorithm, advantages and drawbacks of different methods. Furthermore, these methods were summarized and analyzed in combination with the typical region or typical ecosystems. In general, each method had its own advantages and disadvantages in data acquisition, temporal and spatial resolution. At present, many studies focused on the application of the same method in different regions or grassland types, but few studies focused on the improvement or optimization of the method itself. In addition, even in the same region and the same grassland type, the results of quantitative assessment of natural and anthropogenic factors on vegetation changes of grassland ecosystem varied in different methods. Besides the limitations of their own calculation methods, the results of quantitative assessment of natural and anthropogenic factors were also affected by the spatial and temporal resolution and continuity of the natural and anthropogenic data sources. In the future, we proposed that studies should focus on these aspects:(1) indicator selection was the first step of quantitative assessment, and it is particularly important to select indicators that can represent the changes of grassland ecosystem in different spatial and temporal scale from different perspectives. As for the selection of natural and anthropogenic factors indicators, we should also pay attention to the non-redundancy and non-correlation between indicators; (2) the data sources of natural and anthropogenic indicators were varied in different scales, it is vital to integrate multi-source of quantitative and qualitative data with different temporal and spatial scale to distinguish the contribution of single factor and the interaction between natural and anthropogenic factors in higher spatial and temporal resolution; (3) the improvement of quantitative assessment method itself, breaking through the limitations of existing methods, and developing new ideas and methods of quantitative assessment of natural and anthropogenic factors on vegetation changes of grassland ecosystem, which is also the key point and difficult point of the future research. For the purpose of providing scientific basis and policy guidance for adaptive management of ecosystem and targeted conservation of key ecological functions of ecosystems.