Plant communities are increasingly vulnerable to ecological threats, and they are employing species-to-species facilitation as a strategy to combat drought and safeguard biodiversity. To explore effective defense mechanisms, we analyzed species interactions and developed a model to understand how plant communities evolve and stabilize when facing drought stress, in which validation of existing studies accompanied. Our approach involved several critical steps. Firstly, we selected data from five cities with typical climates to accurately describe drought conditions, including adjusted precipitation equivalents. Secondly, we optimized the Lotka-Volterra competition model and introduced the Competition-Facilitation Model (CFM) with a differential system to unveil the intricate interplay of competition and facilitation among plant species. This included fitting the data and deriving quantitative parameters for the differential equations, thus creating a model that can describe changes in biomass within multi-species communities. We also defined three fundamental roles and a foundational combination (ERC) within simple communities to identify the number and types of high-performing species during successional processes. Thirdly, we conducted an in-depth analysis of biomass fluctuations in response to drought and wet conditions. By artificially intensifying drought frequency and intensity, we unraveled the mechanisms through which plant communities establish stability when facing drought and how species diversity affects different environments.