Abstract: At present, most input data in system dynamic modeling are not able to synchronize with real-world conditions, which often results in inaccurate predictions and/or failure of system control. Dynamic Data Driven Application System (DDDAS) is an innovative paradigm in which real-time computer simulations and measurements, system automated feedback and applications/managements are dynamically integrated. It effectively overcomes setbacks in traditional simulation approaches. This paper is an overview of the emergence and basic concepts of DDDAS and describes the rationale and methodology of DDDAS application in agricultural and environmental sciences through case studies of greenhouse gas emission, irrigation control in crop production and monitoring water pollution in river system. Specific limitations of DDDAS are also discussed.