A stability test equipment for Coal-Water Mixtures (CWM) was constructed. This equipment was able to give both vertical and horizontal sinusoidal oscillation to CWM. The experimental rerults of stability tests under a wide variety of oscillation condition showed that the depth of hard pack layer of CWM was well correlated by the maximum acceleration of sinusoidal motion. Taking into accout of the oscillation condition detected by a tank-truck, the oscillation test conditions for the evaluation of the dynamic stability were proposed as follows