]In recent years, global environmental change has more and more affected the survival of human beings. In order to enhance the observation of the landatmospheric-ocean, the Global Earth Observation System of Systems (GEOSS) and Global Monitoring for Environment and Security (GMES) have been proposed. Data assimilation, the key connection between observation data and model simulations, also gets rapid development. The most significant signs are the continuous introductions of new mathematical achievements into the data assimilation fields. Under the background of the “National Airborne Remote Sensing System—The Earth Science Data Processing Software System”, we review the development of the data assimilation algorithms so as to determine the technical route and major contents of this project and promote the research on data assimilation theory and the development of the software.