Abstract: In order to mastering the precipitation rule of TiN inclusions in continuous casting slab, we compared and analysed that quantity, granularity, and distribution characteristics of TiN inclusions in the slab of titanium microalloyed ultra-low carbon steel, peritectic steel, medium carbon steel and high carbon steel by means of phase analysis facilities such as OM, SEM and Aspex. we found that the particle size and surface density of TiN tended to increase with the increase of carbon content, also found an increasing trend from surface layer of slab to solidification center of slab. we observed that the change of TiN inclusions in slab before and after simulation by using high temperature tube furnace to heating the slab, and analyzed that the reason of TiN change before and after simulated heating.