The experimental study of oxygen transfer performance of clean water and activated sludge mixed liquor in a pilot-scale oxidation ditch of microporous aeration had been carried out. The effect of different aerator arrangement modes (cross, abreast and centralized) on oxygen transfer efficiency were investigated in the experiment. Moreover, the standard oxygen transfer efficiency (SOTE) and oxygen transfer efficiency (OTE) were used as parameters of oxygen transfer performance in the clean water and activated sludge mixed liquor, respectively. The results showed that the oxygen transfer efficiency was affected by the aerator arrangement mode significantly, and the oxygen transfer performances between clean water and activated sludge mixed liquor were different. The oxygen transfer efficiency under the cross aerator arrangement mode was the highest, the abreast aerator arrangement mode was the second, and the centralized aerator arrangement mode was the lowest. In the activated sludge mixed liquor, when the DO concentration was between 1.3 mg/L and 1.7 mg/L, the oxygen consumption of nitrogen removal in different aerator arrangement modes was almost the same. However, the aerator arrangement mode had greater impact on oxygen consumption of COD removal. Compared to the SOTE in the clean water, the OTE in the activated sludge mixed liquor was lower, and the OTE was about 85% of SOTE. Moreover, the OTE was less affected by the aerator arrangement mode than SOTE. To evaluate the aeration performance in the activated sludge mixed liquor, the ratio Z (OTE/SOTE) of oxygen transfer efficiency between the activated sludge mixed liquor and clean water was introduced. Contrary to the regularity of oxygen transfer efficiency under different aerator arrangement modes, the OTE/SOTE was the largest in the centralized aerator arrangement mode and the smallest in the cross aerator arrangement modes. The OTE and SOTE was close under the aerator arrangement mode of low oxygen transfer efficiency.