The Data Assimilation System includes Global Atmospheric Data Assimilation, Ocean Data Assimilation, Land Surface Data assimilation, Atmospheric Chemistry Data Assimilation and Regional Data Assimilation. It employs advanced variational and ensemble methods to provide initial conditions for model simulations and forecasts. It can diagnose, assess and verify the model results, and so support model development and improvement. The core function of the Visualization System is to be responsible for data processing and visualization analysis, providing an essential data visualization platform for the Global Earth Numerical Simulation System, Regional High-Precision Simulation System, and Database and Data Assimilation System of the Earth System Numerical Simulation Facility.