Mixing efficiency in two-phase gas-liquid agitated vessel is one of the important challenges in the industrial processes. Computational fluid dynamics technique (CFD) was used to investigate the effect of four different pitched blade impellers, including 15 degrees, 30 degrees, 45 degrees and 60 degrees, on the mixing quality of gas-liquid agitated vessel. The multiphase flow behavior was modeled by Eulerian-Eulerian multiphase approach, and RNG k - epsilon was used to model the turbulence. The CFD results showed that a strong global vortex plays the main role on the mixing quality of the gas phase in the vessel. Based on the standard deviation criterion, it was observed that the axial distribution of the gas phase in the 30 degrees impeller is about 55% better than the others. In addition, the results showed that the 30 degrees impeller has a uniform radial distribution over the other impellers and the maximum gas phase holdup in the vessel. Investigation of the power consumption of the impellers showed that the 30 degrees impeller has the highest power consumption among the other pitched blade impellers. Also, examine the effect of same power condition for pitched blade impellers showed that the 30 degrees impeller has the best mixing quality in this condition. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.