The Delft3D suite has developed a unique, fully integrated computer software suite for a multi-disciplinary approach and 3D computations for coastal, river and estuarine areas. It can carry out simulations of flows, sediment transports, morphological developments, waves, water quality, and ecology. It has been designed for experts and non-experts alike. The Delft3D software is composed of several modules basing on FLOW hydrodynamic module, grouped around a mutual interface, while being capable to interact with one another. The author describes the theoretical physics model to Delft3D-FLOW, which is based on the Navier- Stokes equations and introduces application of Delft3D on offshore area of Aojiang estuarine in this paper.