Based on the global meteorological forecasting system starting in 1990's, earth system simulation models, such as earth simulator, have been developed and applied to many kind of environmental assessment. This paper introduces the frame work and applications of the Asian Environment Simulator (AES) which consists of main models for atmosphere, land surface, ocean, hydrology, dynamic vegetation, and coastal, river, estuary models and urban air-water environment model. AES has been developed in IDEC, Hiroshima University for international sustainable development and cooperation. Some examples of its application to the Coastal Engineering problems were shown for future development of coastal engineering studies collaborating with river engineering, hydrology, biology and meteorology.