Abstract: The precipitation behavior of inclusions containing Ti in liquid steel and during solidification ofa Tibearing non-quenched and tempered steel was investigated by experiment and thermodynamic calculation. The resuits showed that the size and morphology of inclusions in the non-quenched and tempered steel could be controlled by adjusting the contents of O, Al and Ti, and fine and disperse non-metallic inclusions might be obtained as the nuclei for intra-granular ferrite, which could refine grains and improve the strength and toughness of the steel.