Abstract: The Earth system is a complex, nonlinear, and multi-coupled giant system that integrates the atmosphere, land, ocean, cryosphere, soil, and lithosphere along with their associated organisms through a series of interactive processes. The Earth System Model (ESM) is an advanced mathematical-physical model designed to represent this complex, coupled system. It extends beyond the traditional climate system models that focus primarily on the physical representation of atmospheric, land, and oceanic states. Consequently, the ESM can be utilized not only for weather forecasting and climate prediction, but also for investigating the evolution of the environment and ecosystems as well as the impact of human activities on the climate and ecological environment, and eventually supports the development of rational and optimal strategies for human intervention in natural systems. This paper provides a comprehensive summary of the development history of the Earth System Model and details of individual components of the ESMs. The features of the Chinese Academy of Sciences’ Earth System Model (CAS-ESM), along with its significant achievements and applications in numerical simulation, are elaborated. Finally, some challenges and prospects for further development are delineated.