Abstract: The influence of three effective nucleation particles of Ce₂O₃, ZrO₂ and MgO based on calculations from different heterogeneous nucleation theories oil the refining solidification structure of 16Mn steel was studied by induction furnace contrast experiment. The equiaxed crystal ratio of ingots increases from 32%) to 37% by heterogeneous nucleation MgO particles which are only consistent with the criterion of the lattice disregistry theory; it increases to 40% by ZrO₂ particles which only consist with the criterion of the electrostatic effect theory; and it increases to 44%, by Ce₂O₃ particles which follow the criteria of both the lattice disregistry theory and electrostatic effect theory. Among the above three heterogeneous nucleation particles, Ce₂O₃ has the maximum ability to refine the solidification structure of 16Mn steel. The prior austenite grain size and microstructure of 16Mn steel are refined in different degrees alter the at)ove three kinds of nucleation particles form in molten steel.