Abstract: The floating and collision behavior of inclusions in the floating process was numerically simulated by using the Lattice Boltzmann method. It is found that the floating velocity simulation results of different size inclusion particles are almost the same as the theoretical value,which demonstrates that the motion behavior of solid inclusion particles can be investigated concisely and effectively by using the numerical algorithm adopted in this paper. When an inclusion particle with a diameter of 80 μm locates below an inclusion particle with a diameter of 40 μm and floats up at the same time,the inclusion particle with a diameter of 80 μm can catch up with the inclusion particle with a diameter of 80 μm,collide with each other and grow up into a big inclusion cluster. When the inclusion particles with diameters of 80 μm and 40 μm floats up separately,the floating velocity of the inclusion cluster is bigger than them. For the inclusion particle with a diameter of 40 μm,the floating velocity after collision with the bigger size inclusion particle increases by 300% compared with that of floating separately. In the steelmaking process,it is necessary to take measures to enhance collision and coagulation in the floating process,which will improve the floating velocity of inclusions especially for small size inclusions and have a great importance on the cleanliness of steel.