The bubble growth and departure at the open tip of two capillary tubes joined with a gas chamber was investigated by using a high-speed video imaging system. The experimental results showed that the capillary tube with larger size and hydrophilic property act as the liquid flow channel while the one with smaller size and hydrophobic property as the gas flow channel when liquid submerged the tip of the two capillary tubes without internal gas flow. In contrast, the larger capillary tube become a gas flow channel and the smaller one a liquid flow channel when liquid submerges the tip of the two capillary tubes with internal gas flow. The bubble departure period significantly decreases and the bubble departure diameter eeps in gentle increase with the increase of the flow rate of gas injected into the gas chamber. The liquid flow rate in test section has a significant effect on the bubble growth and departure. A larger liquid flow rate led to a higher bubble departure frequency and a larger bubble departure diameter. At a larger liquid flow rate, the bubble growth and departure at the tip of the upstream capillary become faster, which result in the liquid return at the tip of the downstream capillary tube.