The inclusions formation of low C-Mn and Ti-Al deoxidized steel was investigated by Thermodynamics calculated and experiments . The results are as follows: when Al content in steel is very low ([Al] = 0.0005%), [Ti]<0.009%, the inclusions is the Al2O3-SiO2- MnO-TiOx composite inclusion, and with the increase of the content of Ti, the Al2O3, SiO2, MnO levels become lower, TiOx content increased; when [Ti]≥0.009%,the inclusion is TiOx in the steel. When [Al] = 0.005%, Ti content increased from 0.005% to 0.025%, the inclusion is Al2O3 in the steel. When [Ti]=0.005% and [Al]<0.005% in steel, inclusions is Al2O3-SiO2-MnO-TiOx composite inclusion; [Al]≥0.005% in steel , inclusions is Al2O3. When [Ti]=0.01% and [Al]<0.006%, inclusions is TiOx-Al2O3 composite inclusion in steel, and with the increase of [Al], the Al2O3 increase in composite inclusions; when [Al]≥0.006% , inclusions is Al2O3. The experimental results agree with the thermodynamics conclusions.