Abstract: A flux-form non-hydrostatic dynamic core is developed on the Yin-Yang grid to overcome the limitation of time step and improve the computational efficiency of the model. In order to ensure mass conservation, an explicit flux-form transport scheme and a finite volume method are adopted. A series of idealized three-dimensional experiments with a horizontal resolution of 2.5° are carried out to test the effect of the new frame. The numerical results reveal strong stability and high accuracy. The error of vertical velocity shows an order of about 10^-5 and that of the meridional velocity is about 10^-2 in the balanced flow test. The propagation of the Rossby-Haurwitz wave is well simulated and remains stable without deformation. The Mountain-Rossby wave experiment shows that the trough initiated at the lee side of the mountain develops downstream and propagates to the southern hemisphere.