Numerical study of gas-liquid flow in a wet-type desulphurization absorber is presented and the influences of different inlet and deflector structures on the device performance are identified for optimizing its structure. The dependability of numerical model is validated by the good agreement between the measured and predicted results. Besides, the results of droplet trajectories analyzed by the mechanical formulas are consistent with the simulation results as well. The performance of gas flow field is affected significantly by the inlet structures. The main reason for uneven distribution of liquid-phase is the first layer deflector rather than the gas flow. After removing the first layer deflector, the mass percentage distribution of liquid-phase in the near-wall region is reduced from 68-87% to 25-40%. The temperature distribution and relative humidity depend largely on the distribution of liquid-phase and the gas flow field. Optimized structures improve the pressure drop of device. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.