Based on the Al2O3inclusion analysis of low-carbon aluminum killed steel in tundish of a domestic steel company and fractal theory analysis,a mathematical model of fractal agglomerating-growth of Al2O3inclusions in tundish was established.The results indicated that:large swirl flows exist in both sides of inlet,space between weir and dam,and large zone above outlet,in which monomer and agglomerated inclusion particles accumulate easily;the agglomerated inclusions with hydrodynamic diameter of 6-9.8μm were quickly generated less than 16s,but those inclusions with hydrodynamic diameter more than 11μm were difficult to form;the number density of agglomerated inclusion rapidly increased first,then slowly reduced,so the form and quantity distribution of agglomerated inclusions can be controlled by controlling the residence time of inclusion particles in tundish. Based on the Al2O3inclusion analysis of low-carbon aluminum killed steel in tundish of a domestic steel company and fractal theory analysis, a mathematical model of fractal agglomerating-growth of Al2O3inclusions in tundish was established. The results indicated that: large swirl flows exist in both sides of inlet, space between weir and dam, and large zone above outlet, in which monomer and agglomerated inclusion particles accumulate easily; the agglomerated inclusions with hydrodynamic diameter of 6-9.8 μm were quickly generated less than 16s, but those inclusions with hydrodynamic diameter the number density of agglomerated inclusions rapidly increased first, then slowly reduced, so the form and quantity distribution of agglomerated inclusions can be controlled by controlling the residence time of inclusion particles in tundish.