In order to understand the properties of the winter circulation in the northern China Sea, a two-dimensional numerical model has been established and calculated for an ideal sea basin.In the model we employed a quadratic conservative scheme for a complete set of dynamic and thermodynamic equations. The systematic analysis of stability produced a series of mathematically and physically restrictive conditions which are more general than those derived by Irvine, and Chen.Using this model we made calculations on a series of interesting phenomena, such as the Yellow Sea Warm Current, two gyres in the Yellow Sea, etc. as well as their developing processes. The simulation can also explain the generation mechanism of the phenomena. In order to understand the properties of the winter circulation in the northern China Sea, a two-dimensional numerical model has been established and calculated for an ideal sea basin. The model we employed a quadratic conservative scheme for a complete set of dynamic and thermodynamic equations. The systematic analysis of stability produced a series of mathematically and physically restrictive conditions which are more general than those derived by Irvine, and Chen. Using this model we made calculations on a series of interesting phenomena, such as the Yellow Sea Warm Current, two gyres in the Yellow Sea, etc. as well as their developing processes. The simulation can also explain the generation mechanism of the phenomena.