Abstract: Multiphase microfluidics based on droplets or bubbles is one of the important branches in the microfluidic technology with rapid development in recent years. In this study, an experimental study of gas-liquid two-phase flow regimes and impact factors was conducted in a T-junction microchannel based on high-speed microscope photography and digital image processing technology. Surfactant-added sodium alginate aqueous solutions were selected as the liquid phase, and air was the gas phase. The transition process of the gas-liquid two-phase flow in the T-junction microchannel was studied, and then the bubble flow was classified according to the frequency of bubble generation and the aspect ratio of the generated gas slug in the microchannel. Under the current feeding mode, bubble flow and stratified flow were observed, and the bubble flow could be divided into dispersed bubble flow, short-slug bubble flow and long-slug bubble flow according to the frequency of bubble generation and the aspect ratio of the generated gas slug. Based on the force analysis, the formation mechanisms of the three types of bubble flow were observed as shearing, shearing-to-squeezing and squeezing. The effects of liquid viscosity and surface tension coefficient on the operating range of different types of bubble flows were investigated. It is indicated that liquid viscosity has a greater influence on the operating ranges of bubble flow than that of the surface tension coefficient. The dimensionless correlations of the bubble flow regime transition boundaries were proposed to achieve the controllable operation of the microbubble generation process.