Water jet accompanied with explosive droplets splashing under the various conditions was observed by flow visualization method as a basic study on the droplets control to develop the novel atomization system. Water jet that spouted from nozzle attached to bottom of air pressurized water reservoir naturally draws air from free surface of water in the reservoir and becomes a gas-liquid mixture jet when the free surface of water in the reservoir makes low into some height from the bottom with time elapsed. The gas-liquid mixture jet has made periodic radial splash of water droplets. In this study, the nozzle length and ejection pressure were changed and the droplets splashing phenomenon was analyzed by using high speed visualization and pressure measurement. As a result, it was found that the frequency of aligned droplets was changed due to difference in the nozzle length.