The hydrodynamics and heat transfer of two-dimensional bubble columns operated in Various flow regimes are simultaneously studied using particle image velocimetry and heat transfer probe, respectively. With increasing gas velocity, the flow structures change from dispersed bubble regime to coalesced bubble regime divided into the 4- and 3-region flows. At low gas velocity (< 1 cm/s), the main low structure is the dispersed bubble regime with the uniform distributions of gas holdup, average bubble size, liquid velocity, and heat transfer in the radial direction except near sidewalls. For gas velocity between I and 3 cm/s, the 4-region flow regime begins to take over with the bubble coalescence and interaction in the flow. Macroscopic structures operated in the 4-region flow regime comprise descending, vortical, fast bubble, and central plume regions. In this regime, the fast bubble region has the maximum gas holdup, average bubble size, liquid velocity as well as heat transfer rate due to bubble inducing the strongest turbulent intensity. The vortex in the vortical flow region acts like a close cell to prevent interacting with its surrounding, and leads to unfavorable heat transfer. The heat transfer in the central plume region is better than that in the dispersed bubble regime because it has higher gas velocity to generate larger bubbles from the injector. When gas velocity is over 3 cm/s, the regime becomes the 3-region flow with a large fast bubble stream, no central plume. The path of the center of descending Vortex has the minimum heat transfer rate. On the whole, the 3-region flow regime has the highest heat transfer rate in all three regimes. It is found that the flow and heat transfer are profoundly dominated by the macroscopic hydrodynamics structures.