The paper used FLUENT 6.3.26 software and RNG k-ε turbulence model to perform a two-dimensional simulation of single-phase flow in an integrated oxidation ditch with vertical circle (IODVC). The effect of submerged propeller on the flow fields was explored, and the best installation height and site were obtained. Specifically, the moving reference frame model (MRF), fan model were used to simulate the behaviors of the brush aeration, submerged impeller, respectively. The result showed that the bottom of the central baffle was the danger zone of sludge sedimentation, submerged impeller was installed in the straight place had better flow effect than installation on the bend channel, and 3/4 of the straight was the best installation site. The percentage of the flow regime that liquid velocity was greater than 0.25m/s was maximal when the ratio of axes height and depth (y/h) was 0.18, and the reactor could achieve the greatest effect of circulation flow.