Abstract: In this paper the Factsage7.0 software had been used to calculate the precipitation of titanium-bearing inclusion in the temperature range of 800~1 600℃. The size and morphology of titanium-bearing inclusion of steel with/without adding rare earth had been observed by scanning electron microscopy(SEM) and energy spectrum.Thermodynamics calculation and SEM results show that adding rare earth element Ce can reduce content of harmful elements such as S and O in steel,and thus the Ti₄C₂S₂ and Ti₃O₅ precipitates can be reduced.Therefore,effective Ti content can be increased,which leading to a increasing amount of fine dispersion of Ti(C,N) precipitation.Rare earth Ce can effectively modify the large size TiC-AlO₃ compound inclusions with hard edges and corners into a relatively small size,shape is oval TiC-CeAlO₃ clip,which can reduce the harmful effect of former inclusion shape on properties of steel.