The generation mechanism of acoustically induced jet-like flow has been studied experimentally. When a transducer transmits intense ultrasound into water, acoustic streaming is generated in the medium. If the transducer turns upward, an ultrasonic fountain is observed from the water surface. It has been shown through flow visualization experiments that the generation mechanisms of these two jet-like flows are different: the former is due to the gradient of acoustic radiation pressure in the medium, and the latter is due to the radiation pressure itself acting on the water surface.