Non-uniform flow often results in sludge deposit and other problems in the operation of an integrated oxidation ditch with vertical circle ( IODVC) systems. In this work,the computational fluid dynamics( CFD) technique was applied to conduct a two-dimensional simulation of the liquid-phase flow in an IODVC. Specifically,the moving reference frame model,fan model,and the RNG k-epsilon model were used to describe numerically the behaviors of the aeration brush,submerged impeller,and turbulence in the IODVC,respectively. After model verification,the CFD-based model was used to analyze the impact of guide-plate implementation on the flow-field of the IODVC in comparison with a system without the guide-plate installed. The outcomes suggest that the CFD model can properly portray the velocity distribution throughout the ditch. In addition,the installation of a guide-plate at a proper position can substantially increase the percentage of the high-velocity regime in the main ditch,simultaneously optimizing the flow pattern near the rear of the diversion plate. Overall,guideplate installation is a promising approach to reduce and prevent sludge deposits in the IODVC reactor,providing guidance for future design,and optimization and application of the IODVC.