Abstract: An experimental study on bubble formation of annular and circular nozzles was carried out. The bubble formation was recorded by a high-speed camera and detailed characteristics of bubble formation were obtained. Based on the analysis of the experimental images, the similarities and differences of bubble formation in the two kinds of nozzles were explored. The results show that the bubble formation of the circular nozzle presents the law of bubbling regime, which can be divided into three periods:period-1, period-2 and period-3, while the annular nozzle exhibits only period-3 bubbling regime features when the gas can be ejected stably from the entire annular section. In period-3 bubbling regime, when the subsequent bubble detaches from the two nozzles, the maximum heights of the whole bubble are different. The various forces acting on the bubbles are changing, and the three types of bubble are controlled by different main control forces.