Abstract: Monitoring grassland is important and possible. Multi-Dimensional Sphere Model (MDSM) is a new multivariate data analysis method to analyze the grassland monitoring data. Grassland can be expressed as a point in multivariate space, or a multi-component vector. The magnitude of the vector expresses the biomass of the grassland, but the direction of the vector expresses the composition of the grassland. For temporal dynamic analysis, the composition of the grassland is more important than the production of the grassland, and the ratio of the changes can explain more than the differences do. Both the geometrical and arithmetic series can be adopted to analyze the grassland monitoring data. However, MDSM prefers the geometrical series. Moving average and second degree trend may be introduced to improve the model.