Axial flow pump is the core equipment of ST-Ⅱ polypropylene PDP as a part of loop reactor. As the circulating pump of process fluid, axial flow pump may be operated unstably during actual operation, resulting in the fluctuation of shaft power. To achieve the long-term, safe and stable operation of axial flow pump, it`s important to analyze the internal flow field characteristics and study the internal flow pattern of axial flow pump, mix the process fluid well, obtain uniform distribution of material and temperature and avoid the sedimentation of polymers. Axial flow pump has high requirements for hydraulic performance, so there`s no regulating valve at the suction and discharge of axial flow pump. This paper adopts lifting design method to analyze the axial flow pump with CFD technology, and decreases local vortex motion to avoid the accumulation of process fluid while meeting the hydraulic performance.