Abstract: According to the operating parameters of Jiuquan Iron & Steel Group, the factors, which affect the collision of inclusions and removal rate by coagulation, have been studied through the theoretical analysis and calculation. Increasing stirring energy and temperature of liquid steel is helpful for coagulation between inclusions. In the process of coagulation between inclusions, turbulent collision plays a main role. Inclusion removal by collision is suitable for inclusions having a radius of 1 to 13 μm, whose removal rates are 41.2%-87.8%.