For radical addition polymerization, the viscosity of the fluid rapidly increases with increasing conversion, In such a polymerization, one of the most important characteristics is to mix the entire fluid in the reactor and rapidly remove the reaction heat, For this purpose, we made a large-scale impeller (called an experimental impeller hereafter) which is a combination of a paddle impeller for low viscosity and a half ellipse impeller for high viscosity with the purpose of using it for the wide viscosity range that occurs during polymerization, The effectiveness of the experimental impeller is compared with a multistage pitched blade turbine, anchor impeller, helical screw impeller and helical ribbon impeller based on circulation time, power characteristics, mixing time and mixing efficiency. Actual radical addition polymerization was performed using these impellers. Each impeller is evaluated by comparing the uneven temperature distribution generated in the reactor equipped with the coil and the physical properties of the produced polymer. Furthermore, the change in the heat transfer coefficient of the cooling coil, which is related to the fluid flow, was measured during polymerization using the experimental impeller, a helical screw impeller and a multistage pitched paddle turbine.As a result, it is clarified that this experimental impeller generates strong axial circulation in the polymerization field, so that even with a large change in the viscosity range, polymerization is steadily performed.